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/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DLinq / Dlinq / SqlClient / Query / LongTypeConverter.cs / 1305376 / LongTypeConverter.cs
using System; using System.Collections.Generic; using System.Text; using System.Data.Linq; namespace System.Data.Linq.SqlClient { ////// Converts expressions of type NText, Text, Image to NVarChar(MAX), VarChar(MAX), VarBinary(MAX) /// where necessary. This can only be done on SQL2005, so we add a SqlServerCompatibilityAnnotation /// to the changed nodes. /// internal class LongTypeConverter { Visitor visitor; internal LongTypeConverter(SqlFactory sql) { this.visitor = new Visitor(sql); } internal SqlNode AddConversions(SqlNode node, SqlNodeAnnotations annotations) { visitor.Annotations = annotations; return visitor.Visit(node); } class Visitor : SqlVisitor { SqlFactory sql; SqlNodeAnnotations annotations; internal SqlNodeAnnotations Annotations { set { this.annotations = value; } } internal Visitor(SqlFactory sql) { this.sql = sql; } private SqlExpression ConvertToMax(SqlExpression expr, ProviderType newType) { return sql.UnaryConvert(expr.ClrType, newType, expr, expr.SourceExpression); } // returns CONVERT(VARCHAR/NVARCHAR/VARBINARY(MAX), expr) if provType is one of Text, NText or Image // otherwise just returns expr // changed is true if CONVERT(...(MAX),...) was added private SqlExpression ConvertToMax(SqlExpression expr, out bool changed) { changed = false; if (!expr.SqlType.IsLargeType) return expr; ProviderType newType = sql.TypeProvider.GetBestLargeType(expr.SqlType); changed = true; if (expr.SqlType != newType) { return ConvertToMax(expr, newType); } changed = false; return expr; } private void ConvertColumnsToMax(SqlSelect select, out bool changed, out bool containsLongExpressions) { SqlRow row = select.Row; changed = false; containsLongExpressions = false; foreach (SqlColumn col in row.Columns) { bool columnChanged; containsLongExpressions = containsLongExpressions || col.SqlType.IsLargeType; col.Expression = ConvertToMax(col.Expression, out columnChanged); changed = changed || columnChanged; } } internal override SqlSelect VisitSelect(SqlSelect select) { if (select.IsDistinct) { bool changed; bool containsLongExpressions; ConvertColumnsToMax(select, out changed, out containsLongExpressions); if (containsLongExpressions) { this.annotations.Add(select, new SqlServerCompatibilityAnnotation( Strings.TextNTextAndImageCannotOccurInDistinct(select.SourceExpression), SqlProvider.ProviderMode.Sql2000, SqlProvider.ProviderMode.SqlCE)); } } return base.VisitSelect(select); } internal override SqlNode VisitUnion(SqlUnion su) { bool changedLeft = false; bool containsLongExpressionsLeft = false; SqlSelect left = su.Left as SqlSelect; if (left != null) { ConvertColumnsToMax(left, out changedLeft, out containsLongExpressionsLeft); } bool changedRight = false; bool containsLongExpressionsRight = false; SqlSelect right = su.Right as SqlSelect; if (right != null) { ConvertColumnsToMax(right, out changedRight, out containsLongExpressionsRight); } if (!su.All && (containsLongExpressionsLeft || containsLongExpressionsRight)) { // unless the UNION is 'ALL', the server will perform a DISTINCT operation, // which isn't valid for large types (text, ntext, image) this.annotations.Add(su, new SqlServerCompatibilityAnnotation( Strings.TextNTextAndImageCannotOccurInUnion(su.SourceExpression), SqlProvider.ProviderMode.Sql2000, SqlProvider.ProviderMode.SqlCE)); } return base.VisitUnion(su); } internal override SqlExpression VisitFunctionCall(SqlFunctionCall fc) { if (fc.Name == "LEN") { bool changed; fc.Arguments[0] = ConvertToMax(fc.Arguments[0],out changed); if (fc.Arguments[0].SqlType.IsLargeType) { this.annotations.Add(fc, new SqlServerCompatibilityAnnotation( Strings.LenOfTextOrNTextNotSupported(fc.SourceExpression), SqlProvider.ProviderMode.Sql2000)); } } return base.VisitFunctionCall(fc); } } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
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