NH-3480 - Use ANSI "join" for UPDATE statement

Author: hazzik

src/NHibernate/Persister/Collection/OneToManyPersister.cs

@@ -75,8 +75,7 @@ protected override SqlCommandInfo GenerateDeleteString()
 			else
 			{
 				var ownerPersister = (IOuterJoinLoadable)OwnerEntityPersister;
-				update.SetJoin(ownerPersister.TableName, JoinColumnNames, ownerPersister.GetPropertyColumnNames(CollectionType.LHSPropertyName));
-				update.SetIdentityColumn(ownerPersister.TableName, KeyColumnNames, KeyType);
+				update.SetJoin(ownerPersister.TableName, KeyColumnNames, KeyType, JoinColumnNames, ownerPersister.GetPropertyColumnNames(CollectionType.LHSPropertyName));
 			}
 
 			if (HasIndex)

src/NHibernate/SqlCommand/SqlUpdateBuilder.cs

@@ -1,5 +1,5 @@
 using System.Collections.Generic;
-
+using System.Linq;
 using NHibernate.Engine;
 using NHibernate.SqlTypes;
 using NHibernate.Type;
@@ -20,9 +20,7 @@ public class SqlUpdateBuilder : SqlBaseBuilder, ISqlStringBuilder
 		// columns-> (ColumnName, Value) or (ColumnName, SqlType) for parametrized column
 		private readonly LinkedHashMap<string, object> columns = new LinkedHashMap<string, object>();
 
-		private SqlString join = null;
-
-		private List<SqlString> whereStrings = new List<SqlString>();
+	    private List<SqlString> whereStrings = new List<SqlString>();
 		private readonly List<SqlType> whereParameterTypes = new List<SqlType>();
 		private SqlString assignments;
 
@@ -130,25 +128,30 @@ public SqlUpdateBuilder AppendAssignmentFragment(SqlString fragment)
 			return this;
 		}
 
-		public SqlUpdateBuilder SetJoin(string joinTableName, string[] lhsColumnNames, string[] rhsColumnNames)
+		public SqlUpdateBuilder SetJoin(string joinTableName, string[] keyColumnNames, IType identityType, string[] lhsColumnNames, string[] rhsColumnNames)
 		{
-			SqlStringBuilder joinStringBuilder = new SqlStringBuilder();
+			var sqlBuilder = new SqlStringBuilder()
+				.Add("EXISTS (SELECT * FROM ")
+				.Add(joinTableName)
+				.Add(" WHERE ")
+				.Add(ToWhereString(joinTableName, keyColumnNames));
 
-			joinStringBuilder.Add(" INNER JOIN ");
-			joinStringBuilder.Add(joinTableName);
-			joinStringBuilder.Add(" ON ");
-			bool andNeeded = false;
 			for (int columnIndex = 0; columnIndex < lhsColumnNames.Length; columnIndex++)
 			{
-				if (andNeeded)
-				{
-					joinStringBuilder.Add(" AND ");
-				}
-				joinStringBuilder.Add(tableName + StringHelper.Dot + lhsColumnNames[columnIndex] + " = " + joinTableName + StringHelper.Dot + rhsColumnNames[columnIndex]);
-				andNeeded = true;
+				sqlBuilder.Add(" AND ")
+					.Add(tableName)
+					.Add(StringHelper.Dot.ToString())
+					.Add(lhsColumnNames[columnIndex])
+					.Add("=")
+					.Add(joinTableName)
+					.Add(StringHelper.Dot.ToString())
+					.Add(rhsColumnNames[columnIndex]);
 			}
+			sqlBuilder.Add(")");
+
+			whereStrings.Add(sqlBuilder.ToSqlString());
+			whereParameterTypes.AddRange(identityType.SqlTypes(Mapping));
 
-			join = joinStringBuilder.ToSqlString();
 			return this;
 		}
 
@@ -174,20 +177,6 @@ public SqlUpdateBuilder SetIdentityColumn(string[] columnNames, IType identityTy
 			return this;
 		}
 
- 		/// <summary>
-		/// Sets the IdentityColumn for the <c>UPDATE</c> sql to use.
-		/// </summary>
-		/// <param name="tableName">Table name to prepend to the columns.</param>
-		/// <param name="columnNames">An array of the column names for the Property</param>
-		/// <param name="identityType">The IType of the Identity Property.</param>
-		/// <returns>The SqlUpdateBuilder.</returns>
-		public SqlUpdateBuilder SetIdentityColumn(string tableName, string[] columnNames, IType identityType)
-		{
-			whereStrings.Add(ToWhereString(tableName, columnNames));
-			whereParameterTypes.AddRange(identityType.SqlTypes(Mapping));
-			return this;
-		}
-
 		/// <summary>
 		/// Sets the VersionColumn for the <c>UPDATE</c> sql to use.
 		/// </summary>
@@ -271,19 +260,14 @@ public SqlString ToSqlString()
 				initialCapacity += (columns.Count - 1) + (columns.Count * 3);
 			}
 
-			// 3 - JOIN
-			if (join != null)
-				initialCapacity += 3;
-
 			// 1 = "WHERE" 
 			initialCapacity++;
 
 			// the "AND" before all but the first whereString
 			if (whereStrings.Count > 0)
 			{
 				initialCapacity += (whereStrings.Count - 1);
-				foreach (SqlString whereString in whereStrings)
-					initialCapacity += whereString.Count;
+				initialCapacity += whereStrings.Sum(x => x.Count);
 			}
 
 			if (!string.IsNullOrEmpty(comment))
@@ -325,12 +309,6 @@ public SqlString ToSqlString()
 				sqlBuilder.Add(assignments);
 			}
 
-			if (join != null)
-			{
-				sqlBuilder.Add(" FROM ");
-				sqlBuilder.Add(tableName);
-				sqlBuilder.Add(join);
-			}
 
 			sqlBuilder.Add(" WHERE ");
 			bool andNeeded = false;