DmlSqlGenerator.cs source code in C# .NET

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/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / SqlClient / SqlGen / DmlSqlGenerator.cs / 1305376 / DmlSqlGenerator.cs

                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner  [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

using System; 
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO; 
using System.Text;
using System.Data.Common; 
using System.Data.SqlClient; 
using System.Data.Metadata.Edm;
using System.Data.Common.CommandTrees; 
using System.Data.Common.Utils;
using System.Data.Mapping.Update.Internal;
using System.Data.Mapping;
using System.Linq; 

namespace System.Data.SqlClient.SqlGen 
{ 
    /// 
    /// Class generating SQL for a DML command tree. 
    /// 
    internal static class DmlSqlGenerator
    {
        private const int s_commandTextBuilderInitialCapacity = 256; 
        private const string s_generatedValuesVariableName = "@generated_keys";
 
        internal static string GenerateUpdateSql(DbUpdateCommandTree tree, SqlVersion sqlVersion, out List parameters) 
        {
            const string dummySetParameter = "@p"; 

            StringBuilder commandText = new StringBuilder(s_commandTextBuilderInitialCapacity);
            ExpressionTranslator translator = new ExpressionTranslator(commandText, tree, null != tree.Returning, sqlVersion);
 
            if (tree.SetClauses.Count == 0)
            { 
                commandText.AppendLine("declare " + dummySetParameter + " int"); 
            }
 
            // update [schemaName].[tableName]
            commandText.Append("update ");
            tree.Target.Expression.Accept(translator);
            commandText.AppendLine(); 

            // set c1 = ..., c2 = ..., ... 
            bool first = true; 
            commandText.Append("set ");
            foreach (DbSetClause setClause in tree.SetClauses) 
            {
                if (first) { first = false; }
                else { commandText.Append(", "); }
                setClause.Property.Accept(translator); 
                commandText.Append(" = ");
                setClause.Value.Accept(translator); 
            } 

            if (first) 
            {
                // If first is still true, it indicates there were no set
                // clauses. Introduce a fake set clause so that:
                // - we acquire the appropriate locks 
                // - server-gen columns (e.g. timestamp) get recomputed
                // 
                // We use the following pattern: 
                //
                //  update Foo 
                //  set @p = 0
                //  where ...
                commandText.Append(dummySetParameter + " = 0");
            } 
            commandText.AppendLine();
 
            // where c1 = ..., c2 = ... 
            commandText.Append("where ");
            tree.Predicate.Accept(translator); 
            commandText.AppendLine();

            // generate returning sql
            GenerateReturningSql(commandText, tree, null, translator, tree.Returning, false); 

            parameters = translator.Parameters; 
            return commandText.ToString(); 
        }
 
        internal static string GenerateDeleteSql(DbDeleteCommandTree tree, SqlVersion sqlVersion, out List parameters)
        {
            StringBuilder commandText = new StringBuilder(s_commandTextBuilderInitialCapacity);
            ExpressionTranslator translator = new ExpressionTranslator(commandText, tree, false, sqlVersion); 

            // delete [schemaName].[tableName] 
            commandText.Append("delete "); 
            tree.Target.Expression.Accept(translator);
            commandText.AppendLine(); 

            // where c1 = ... AND c2 = ...
            commandText.Append("where ");
            tree.Predicate.Accept(translator); 

            parameters = translator.Parameters; 
            return commandText.ToString(); 
        }
 
        internal static string GenerateInsertSql(DbInsertCommandTree tree, SqlVersion sqlVersion, out List parameters)
        {
            StringBuilder commandText = new StringBuilder(s_commandTextBuilderInitialCapacity);
            ExpressionTranslator translator = new ExpressionTranslator(commandText, tree, 
                null != tree.Returning, sqlVersion);
 
            bool useGeneratedValuesVariable = UseGeneratedValuesVariable(tree, sqlVersion, translator); 
            EntityType tableType = (EntityType)((DbScanExpression)tree.Target.Expression).Target.ElementType;
 
            if (useGeneratedValuesVariable)
            {
                // manufacture the variable, e.g. "declare @generated_values table(id uniqueidentifier)"
                commandText 
                    .Append("declare ")
                    .Append(s_generatedValuesVariableName) 
                    .Append(" table("); 
                bool first = true;
                foreach (EdmMember column in tableType.KeyMembers) 
                {
                    if (first)
                    {
                        first = false; 
                    }
                    else 
                    { 
                        commandText.Append(", ");
                    } 
                    string columnType = SqlGenerator.GenerateSqlForStoreType(sqlVersion, column.TypeUsage);
                    if (columnType == "rowversion" || columnType == "timestamp")
                    {
                        // rowversion and timestamp are intrinsically read-only. use binary to gather server generated 
                        // values for these types.
                        columnType = "binary(8)"; 
                    } 
                    commandText
                        .Append(GenerateMemberTSql(column)) 
                        .Append(" ")
                        .Append(columnType);
                    Facet collationFacet;
                    if (column.TypeUsage.Facets.TryGetValue(DbProviderManifest.CollationFacetName, false, out collationFacet)) 
                    {
                        string collation = collationFacet.Value as string; 
                        if (!string.IsNullOrEmpty(collation)) 
                        {
                            commandText.Append(" collate ").Append(collation); 
                        }
                    }
                }
                Debug.Assert(!first, "if useGeneratedValuesVariable is true, it implies some columns do not have values"); 
                commandText.AppendLine(")");
            } 
 
            // insert [schemaName].[tableName]
            commandText.Append("insert "); 
            tree.Target.Expression.Accept(translator);

            if (0 < tree.SetClauses.Count)
            { 
                // (c1, c2, c3, ...)
                commandText.Append("("); 
                bool first = true; 
                foreach (DbSetClause setClause in tree.SetClauses)
                { 
                    if (first) { first = false; }
                    else { commandText.Append(", "); }
                    setClause.Property.Accept(translator);
                } 
                commandText.AppendLine(")");
            } 
            else 
            {
                commandText.AppendLine(); 
            }

            if (useGeneratedValuesVariable)
            { 
                // output inserted.id into @generated_values
                commandText.Append("output "); 
                bool first = true; 
                foreach (EdmMember column in tableType.KeyMembers)
                { 
                    if (first)
                    {
                        first = false;
                    } 
                    else
                    { 
                        commandText.Append(", "); 
                    }
                    commandText.Append("inserted."); 
                    commandText.Append(GenerateMemberTSql(column));
                }
                commandText
                    .Append(" into ") 
                    .AppendLine(s_generatedValuesVariableName);
            } 
 
            if (0 < tree.SetClauses.Count)
            { 
                // values c1, c2, ...
                bool first = true;
                commandText.Append("values (");
                foreach (DbSetClause setClause in tree.SetClauses) 
                {
                    if (first) { first = false; } 
                    else { commandText.Append(", "); } 
                    setClause.Value.Accept(translator);
 
                    translator.RegisterMemberValue(setClause.Property, setClause.Value);
                }
                commandText.AppendLine(")");
            } 
            else
            { 
                // default values 
                commandText.AppendLine("default values");
            } 
            // generate returning sql
            GenerateReturningSql(commandText, tree, tableType, translator, tree.Returning, useGeneratedValuesVariable);

            parameters = translator.Parameters; 
            return commandText.ToString();
        } 
 
        /// 
        /// Determine whether we should use a generated values variable to return server generated values. 
        /// This is true when we're attempting to insert a row where the primary key is server generated
        /// but is not an integer type (and therefore can't be used with scope_identity()). It is also true
        /// where there is a compound server generated key.
        ///  
        private static bool UseGeneratedValuesVariable(DbInsertCommandTree tree, SqlVersion sqlVersion, ExpressionTranslator translator)
        { 
            bool useGeneratedValuesVariable = false; 
            if (sqlVersion > SqlVersion.Sql8 && tree.Returning != null)
            { 
                // Figure out which columns have values
                HashSet columnsWithValues = new HashSet(tree.SetClauses.Cast().Select(s => ((DbPropertyExpression)s.Property).Property));

                // Only SQL Server 2005+ support an output clause for inserts 
                bool firstKeyFound = false;
                foreach (EdmMember keyMember in ((DbScanExpression)tree.Target.Expression).Target.ElementType.KeyMembers) 
                { 
                    if (!columnsWithValues.Contains(keyMember))
                    { 
                        if (firstKeyFound)
                        {
                            // compound server gen key
                            useGeneratedValuesVariable = true; 
                            break;
                        } 
                        else 
                        {
                            firstKeyFound = true; 
                            if (!IsValidScopeIdentityColumnType(keyMember.TypeUsage))
                            {
                                // unsupported type
                                useGeneratedValuesVariable = true; 
                                break;
                            } 
                        } 
                    }
                } 
            }
            return useGeneratedValuesVariable;
        }
 
        // Generates T-SQL describing a member
        // Requires: member must belong to an entity type (a safe requirement for DML 
        // SQL gen, where we only access table columns) 
        private static string GenerateMemberTSql(EdmMember member)
        { 
            EntityType entityType = (EntityType)member.DeclaringType;
            string sql;
            if (!entityType.TryGetMemberSql(member, out sql))
            { 
                sql = SqlGenerator.QuoteIdentifier(member.Name);
                entityType.SetMemberSql(member, sql); 
            } 
            return sql;
        } 

        /// 
        /// Generates SQL fragment returning server-generated values.
        /// Requires: translator knows about member values so that we can figure out 
        /// how to construct the key predicate.
        ///  
        /// Sample SQL: 
        ///
        ///     select IdentityValue 
        ///     from dbo.MyTable
        ///     where @@ROWCOUNT > 0 and IdentityValue = scope_identity()
        ///
        /// or 
        ///
        ///     select TimestampValue 
        ///     from dbo.MyTable 
        ///     where @@ROWCOUNT > 0 and Id = 1
        /// 
        /// Note that we filter on rowcount to ensure no rows are returned if no rows were modified.
        ///
        /// On SQL Server 2005 and up, we have an additional syntax used for non integer return types:
        /// 
        ///     declare @generatedValues table(ID uniqueidentifier)
        ///     insert dbo.MyTable 
        ///     output ID into @generated_values 
        ///     values (...);
        ///     select ID 
        ///     from @generatedValues as g join dbo.MyTable as t on g.ID = t.ID
        ///     where @@ROWCOUNT > 0;
        /// 
        ///  
        /// Builder containing command text
        /// Modification command tree 
        /// Type of table. 
        /// Translator used to produce DML SQL statement
        /// for the tree 
        /// Returning expression. If null, the method returns
        /// immediately without producing a SELECT statement.
        private static void GenerateReturningSql(StringBuilder commandText, DbModificationCommandTree tree, EntityType tableType,
            ExpressionTranslator translator, DbExpression returning, bool useGeneratedValuesVariable) 
        {
            // Nothing to do if there is no Returning expression 
            if (null == returning) { return; } 

            // select 
            commandText.Append("select ");
            if (useGeneratedValuesVariable)
            {
                translator.PropertyAlias = "t"; 
            }
            returning.Accept(translator); 
            if (useGeneratedValuesVariable) 
            {
                translator.PropertyAlias = null; 
            }
            commandText.AppendLine();

            if (useGeneratedValuesVariable) 
            {
                // from @generated_values 
                commandText.Append("from "); 
                commandText.Append(s_generatedValuesVariableName);
                commandText.Append(" as g join "); 
                tree.Target.Expression.Accept(translator);
                commandText.Append(" as t on ");
                string separator = string.Empty;
                foreach (EdmMember keyMember in tableType.KeyMembers) 
                {
                    commandText.Append(separator); 
                    separator = " and "; 
                    commandText.Append("g.");
                    string memberTSql = GenerateMemberTSql(keyMember); 
                    commandText.Append(memberTSql);
                    commandText.Append(" = t.");
                    commandText.Append(memberTSql);
                } 
                commandText.AppendLine();
                commandText.Append("where @@ROWCOUNT > 0"); 
            } 
            else
            { 
                // from
                commandText.Append("from ");
                tree.Target.Expression.Accept(translator);
                commandText.AppendLine(); 

                // where 
                commandText.Append("where @@ROWCOUNT > 0"); 
                EntitySetBase table = ((DbScanExpression)tree.Target.Expression).Target;
                bool identity = false; 
                foreach (EdmMember keyMember in table.ElementType.KeyMembers)
                {
                    commandText.Append(" and ");
                    commandText.Append(GenerateMemberTSql(keyMember)); 
                    commandText.Append(" = ");
 
                    // retrieve member value sql. the translator remembers member values 
                    // as it constructs the DML statement (which precedes the "returning"
                    // SQL) 
                    SqlParameter value;
                    if (translator.MemberValues.TryGetValue(keyMember, out value))
                    {
                        commandText.Append(value.ParameterName); 
                    }
                    else 
                    { 
                        // if no value is registered for the key member, it means it is an identity
                        // which can be retrieved using the scope_identity() function 
                        if (identity)
                        {
                            // there can be only one server generated key
                            throw EntityUtil.NotSupported(System.Data.Entity.Strings.Update_NotSupportedServerGenKey(table.Name)); 
                        }
 
                        if (!IsValidScopeIdentityColumnType(keyMember.TypeUsage)) 
                        {
                            throw EntityUtil.InvalidOperation(System.Data.Entity.Strings.Update_NotSupportedIdentityType( 
                                keyMember.Name, keyMember.TypeUsage.ToString()));
                        }

                        commandText.Append("scope_identity()"); 
                        identity = true;
                    } 
                } 
            }
        } 

        private static bool IsValidScopeIdentityColumnType(TypeUsage typeUsage)
        {
            // SQL Server supports the following types for identity columns: 
            // tinyint, smallint, int, bigint, decimal(p,0), or numeric(p,0)
 
            // make sure it's a primitive type 
            if (typeUsage.EdmType.BuiltInTypeKind != BuiltInTypeKind.PrimitiveType)
            { 
                return false;
            }

            // check if this is a supported primitive type (compare by name) 
            string typeName = typeUsage.EdmType.Name;
 
            // integer types 
            if (typeName == "tinyint" || typeName == "smallint" ||
                typeName == "int" || typeName == "bigint") 
            {
                return true;
            }
 
            // variable scale types (require scale = 0)
            if (typeName == "decimal" || typeName == "numeric") 
            { 
                Facet scaleFacet;
                return (typeUsage.Facets.TryGetValue(DbProviderManifest.ScaleFacetName, 
                    false, out scaleFacet) && Convert.ToInt32(scaleFacet.Value, CultureInfo.InvariantCulture) == 0);
            }

            // type not in supported list 
            return false;
        } 
 
        /// 
        /// Lightweight expression translator for DML expression trees, which have constrained 
        /// scope and support.
        /// 
        private class ExpressionTranslator : BasicExpressionVisitor
        { 
            /// 
            /// Initialize a new expression translator populating the given string builder 
            /// with command text. Command text builder and command tree must not be null. 
            /// 
            /// Command text with which to populate commands 
            /// Command tree generating SQL
            /// Indicates whether the translator should preserve
            /// member values while compiling t-SQL (only needed for server generation)
            internal ExpressionTranslator(StringBuilder commandText, DbModificationCommandTree commandTree, 
                bool preserveMemberValues, SqlVersion version)
            { 
                Debug.Assert(null != commandText); 
                Debug.Assert(null != commandTree);
                _commandText = commandText; 
                _commandTree = commandTree;
                _version = version;
                _parameters = new List();
                _memberValues = preserveMemberValues ? new Dictionary() : 
                    null;
            } 
 
            private readonly StringBuilder _commandText;
            private readonly DbModificationCommandTree _commandTree; 
            private readonly List _parameters;
            private readonly Dictionary _memberValues;
            private readonly static AliasGenerator s_parameterNames = new AliasGenerator("@", 1000);
            private readonly SqlVersion _version; 

            internal List Parameters { get { return _parameters; } } 
            internal Dictionary MemberValues { get { return _memberValues; } } 
            internal string PropertyAlias { get; set; }
 
            // generate parameter (name based on parameter ordinal)
            internal SqlParameter CreateParameter(object value, TypeUsage type)
            {
                // Suppress the MaxLength facet in the type usage because 
                // SqlClient will silently truncate data when SqlParameter.Size < |SqlParameter.Value|.
                const bool preventTruncation = true; 
                SqlParameter parameter = SqlProviderServices.CreateSqlParameter(s_parameterNames.GetName(_parameters.Count), type, ParameterMode.In, value, preventTruncation, _version); 

                _parameters.Add(parameter); 

                return parameter;
            }
 
            public override void Visit(DbAndExpression expression)
            { 
                VisitBinary(expression, " and "); 
            }
 
            public override void Visit(DbOrExpression expression)
            {
                VisitBinary(expression, " or ");
            } 

            public override void Visit(DbComparisonExpression expression) 
            { 
                Debug.Assert(expression.ExpressionKind == DbExpressionKind.Equals,
                    "only equals comparison expressions are produced in DML command trees in V1"); 

                VisitBinary(expression, " = ");

                RegisterMemberValue(expression.Left, expression.Right); 
            }
 
            ///  
            /// Call this method to register a property value pair so the translator "remembers"
            /// the values for members of the row being modified. These values can then be used 
            /// to form a predicate for server-generation (based on the key of the row)
            /// 
            /// DbExpression containing the column reference (property expression).
            /// DbExpression containing the value of the column. 
            internal void RegisterMemberValue(DbExpression propertyExpression, DbExpression value)
            { 
                if (null != _memberValues) 
                {
                    // register the value for this property 
                    Debug.Assert(propertyExpression.ExpressionKind == DbExpressionKind.Property,
                        "DML predicates and setters must be of the form property = value");

                    // get name of left property 
                    EdmMember property = ((DbPropertyExpression)propertyExpression).Property;
 
                    // don't track null values 
                    if (value.ExpressionKind != DbExpressionKind.Null)
                    { 
                        Debug.Assert(value.ExpressionKind == DbExpressionKind.Constant,
                            "value must either constant or null");
                        // retrieve the last parameter added (which describes the parameter)
                        _memberValues[property] = _parameters[_parameters.Count - 1]; 
                    }
                } 
            } 

            public override void Visit(DbIsNullExpression expression) 
            {
                expression.Argument.Accept(this);
                _commandText.Append(" is null");
            } 

            public override void Visit(DbNotExpression expression) 
            { 
                _commandText.Append("not (");
                expression.Accept(this); 
                _commandText.Append(")");
            }

            public override void Visit(DbConstantExpression expression) 
            {
                SqlParameter parameter = CreateParameter(expression.Value, expression.ResultType); 
                _commandText.Append(parameter.ParameterName); 
            }
 
            public override void Visit(DbScanExpression expression)
            {
                // we know we won't hit this code unless there is no function defined for this
                // ModificationOperation, so if this EntitySet is using a DefiningQuery, instead 
                // of a table, that is an error
                if (expression.Target.DefiningQuery != null) 
                { 
                    string missingCudElement;
                    if (_commandTree.CommandTreeKind == DbCommandTreeKind.Delete) 
                    {
                        missingCudElement = StorageMslConstructs.DeleteFunctionElement;
                    }
                    else if (_commandTree.CommandTreeKind == DbCommandTreeKind.Insert) 
                    {
                        missingCudElement = StorageMslConstructs.InsertFunctionElement; 
                    } 
                    else
                    { 
                        Debug.Assert(_commandTree.CommandTreeKind == DbCommandTreeKind.Update, "did you add a new option?");
                        missingCudElement = StorageMslConstructs.UpdateFunctionElement;
                    }
                    throw EntityUtil.Update(System.Data.Entity.Strings.Update_SqlEntitySetWithoutDmlFunctions(expression.Target.Name, missingCudElement, StorageMslConstructs.ModificationFunctionMappingElement), null); 
                }
 
                _commandText.Append(SqlGenerator.GetTargetTSql(expression.Target)); 
            }
 
            public override void Visit(DbPropertyExpression expression)
            {
                if (!string.IsNullOrEmpty(this.PropertyAlias))
                { 
                    _commandText.Append(this.PropertyAlias);
                    _commandText.Append("."); 
                } 
                _commandText.Append(GenerateMemberTSql(expression.Property));
            } 

            public override void Visit(DbNullExpression expression)
            {
                _commandText.Append("null"); 
            }
 
            public override void Visit(DbNewInstanceExpression expression) 
            {
                // assumes all arguments are self-describing (no need to use aliases 
                // because no renames are ever used in the projection)
                bool first = true;
                foreach (DbExpression argument in expression.Arguments)
                { 
                    if (first) { first = false; }
                    else { _commandText.Append(", "); } 
                    argument.Accept(this); 
                }
            } 

            private void VisitBinary(DbBinaryExpression expression, string separator)
            {
                _commandText.Append("("); 
                expression.Left.Accept(this);
                _commandText.Append(separator); 
                expression.Right.Accept(this); 
                _commandText.Append(")");
            } 

        }
    }
} 


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
                        

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