Added the ability to delete multiple columns at once.

src/FluentMigrator.Runner/Generators/Generic/GenericGenerator.cs

@@ -1,11 +1,11 @@
 using System;
 using System.Collections.Generic;
+using System.Data;
+using System.Linq;
 using System.Text;
 using FluentMigrator.Expressions;
 using FluentMigrator.Model;
 using FluentMigrator.Runner.Generators.Base;
-using System.Linq;
-using System.Data;
 
 namespace FluentMigrator.Runner.Generators.Generic
 {
@@ -92,7 +92,13 @@ public override string Generate(AlterColumnExpression expression)
 
         public override string Generate(DeleteColumnExpression expression)
         {
-            return String.Format(DropColumn, Quoter.QuoteTableName(expression.TableName), Quoter.QuoteColumnName(expression.ColumnName));
+            StringBuilder builder = new StringBuilder();
+            foreach (string columnName in expression.ColumnNames) 
+            {
+                if (expression.ColumnNames.First() != columnName) builder.AppendLine(";");
+                builder.AppendFormat(DropColumn, Quoter.QuoteTableName(expression.TableName), Quoter.QuoteColumnName(columnName));
+            }
+            return builder.ToString();
         }
 
         public override string Generate(RenameColumnExpression expression)

src/FluentMigrator.Runner/Generators/Postgres/PostgresGenerator.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Text;
 using FluentMigrator.Expressions;
 using FluentMigrator.Model;
@@ -44,7 +45,15 @@ public override string Generate(DeleteTableExpression expression)
 
         public override string Generate(DeleteColumnExpression expression)
         {
-            return string.Format("ALTER TABLE {0}.{1} DROP COLUMN {2}", Quoter.QuoteSchemaName(expression.SchemaName), Quoter.QuoteTableName(expression.TableName), Quoter.QuoteColumnName(expression.ColumnName));
+            StringBuilder builder = new StringBuilder();
+            foreach (string columnName in expression.ColumnNames) {
+                if (expression.ColumnNames.First() != columnName) builder.AppendLine(";");
+                builder.AppendFormat("ALTER TABLE {0}.{1} DROP COLUMN {2}", 
+                    Quoter.QuoteSchemaName(expression.SchemaName), 
+                    Quoter.QuoteTableName(expression.TableName), 
+                    Quoter.QuoteColumnName(columnName));
+            }
+            return builder.ToString();
         }
 
         public override string Generate(CreateForeignKeyExpression expression)

src/FluentMigrator.Runner/Generators/SqlServer/SqlServer2000Generator.cs

@@ -17,6 +17,7 @@
 #endregion
 
 using System;
+using System.Linq;
 using System.Text;
 using FluentMigrator.Expressions;
 using FluentMigrator.Runner.Extensions;
@@ -67,20 +68,28 @@ public override string Generate(DeleteColumnExpression expression)
             // before we drop a column, we have to drop any default value constraints in SQL Server
             var builder = new StringBuilder();
 
-            builder.AppendLine(Generate(new DeleteDefaultConstraintExpression
-                                            {
-                                                ColumnName = expression.ColumnName,
-                                                SchemaName = expression.SchemaName,
-                                                TableName = expression.TableName
-                                            }));
+            foreach (string column in expression.ColumnNames) 
+            {
+                if (expression.ColumnNames.First() != column) builder.AppendLine("GO");
+                BuildDelete(expression, column, builder);  
+            }
+
+            return builder.ToString();
+        }
 
-            builder.AppendLine();
+        protected virtual void BuildDelete(DeleteColumnExpression expression, string columnName, StringBuilder builder) 
+        {
+            builder.AppendLine(Generate(new DeleteDefaultConstraintExpression {
+                                                                                  ColumnName = columnName,
+                                                                                  SchemaName = expression.SchemaName,
+                                                                                  TableName = expression.TableName
+                                                                              }));
 
-            builder.Append(String.Format("-- now we can finally drop column\r\nALTER TABLE {0} DROP COLUMN {1};",
-                Quoter.QuoteTableName(expression.TableName),
-                Quoter.QuoteColumnName(expression.ColumnName)));
+            builder.AppendLine();
 
-            return builder.ToString();
+            builder.AppendLine(String.Format("-- now we can finally drop column\r\nALTER TABLE {0} DROP COLUMN {1};",
+                                         Quoter.QuoteTableName(expression.TableName),
+                                         Quoter.QuoteColumnName(columnName)));
         }
 
         public override string Generate(AlterDefaultConstraintExpression expression)

src/FluentMigrator.Runner/Generators/SqlServer/SqlServer2005Generator.cs

@@ -238,26 +238,20 @@ public override string Generate(DeleteIndexExpression expression)
             return String.Format(DropIndex, Quoter.QuoteIndexName(expression.Index.Name), Quoter.QuoteSchemaName(expression.Index.SchemaName), Quoter.QuoteTableName(expression.Index.TableName));
         }
 
-        public override string Generate(DeleteColumnExpression expression)
+        protected override void BuildDelete(DeleteColumnExpression expression, string columnName, StringBuilder builder) 
         {
-            // before we drop a column, we have to drop any default value constraints in SQL Server
-            var builder = new StringBuilder();
-
-            builder.AppendLine(Generate(new DeleteDefaultConstraintExpression
-            {
-                ColumnName = expression.ColumnName,
-                SchemaName = expression.SchemaName,
-                TableName = expression.TableName
-            }));
+            builder.AppendLine(Generate(new DeleteDefaultConstraintExpression {
+                                                                                  ColumnName = columnName,
+                                                                                  SchemaName = expression.SchemaName,
+                                                                                  TableName = expression.TableName
+                                                                              }));
 
             builder.AppendLine();
 
-            builder.Append(String.Format("-- now we can finally drop column\r\nALTER TABLE {2}.{0} DROP COLUMN {1};",
-               Quoter.QuoteTableName(expression.TableName),
-               Quoter.QuoteColumnName(expression.ColumnName),
-               Quoter.QuoteSchemaName(expression.SchemaName)));
-
-            return builder.ToString();
+            builder.AppendLine(String.Format("-- now we can finally drop column\r\nALTER TABLE {2}.{0} DROP COLUMN {1};",
+                                         Quoter.QuoteTableName(expression.TableName),
+                                         Quoter.QuoteColumnName(columnName),
+                                         Quoter.QuoteSchemaName(expression.SchemaName)));
         }
 
         public override string Generate(AlterDefaultConstraintExpression expression)

src/FluentMigrator.Runner/Generators/SqlServer/SqlServerCeGenerator.cs

@@ -18,6 +18,7 @@
 #endregion
 
 using System;
+using System.Linq;
 using FluentMigrator.Expressions;
 
 namespace FluentMigrator.Runner.Generators.SqlServer
@@ -56,7 +57,7 @@ public override string Generate(DeleteColumnExpression expression)
         {
             // Limited functionality in CE, for now will just drop the column.. no DECLARE support!
             const string sql = @"ALTER TABLE {0} DROP COLUMN {1};";
-            return String.Format(sql, Quoter.QuoteTableName(expression.TableName), Quoter.QuoteColumnName(expression.ColumnName));
+            return String.Format(sql, Quoter.QuoteTableName(expression.TableName), Quoter.QuoteColumnName(expression.ColumnNames.ElementAt(0)));
         }
 
         public override string Generate(DeleteIndexExpression expression)

src/FluentMigrator.Tests/Unit/Builders/Delete/DeleteColumnExpressionBuilderTests.cs

@@ -16,6 +16,8 @@
 //
 #endregion
 
+using System.Collections.Generic;
+using System.Linq;
 using FluentMigrator.Builders.Delete.Column;
 using FluentMigrator.Expressions;
 using Moq;
@@ -36,5 +38,28 @@ public void CallingFromTableSetsTableName()
 
             expressionMock.VerifySet(x => x.TableName = "Bacon");
         }
+
+        [Test]
+        public void CallingColumnAddsColumnNameToList() 
+        {
+            var expressionMock = new Mock<DeleteColumnExpression>();
+            expressionMock.Object.ColumnNames = new List<string> {"Cheese"};
+
+            var builder = new DeleteColumnExpressionBuilder(expressionMock.Object);
+            builder.Column("Bacon");
+
+            Assert.That(expressionMock.Object.ColumnNames.ElementAt(1), Is.EqualTo("Bacon"));
+        }
+
+        [Test]
+        public void CallingInSchemaSetsSchemaOnExpression() 
+        {
+            var expressionMock = new Mock<DeleteColumnExpression>();
+
+            var builder = new DeleteColumnExpressionBuilder(expressionMock.Object);
+            builder.InSchema("Bacon");
+
+            expressionMock.VerifySet(x => x.SchemaName = "Bacon");
+        }
     }
 }

src/FluentMigrator.Tests/Unit/Builders/Delete/DeleteExpressionRootTests.cs

@@ -17,6 +17,7 @@
 #endregion
 
 using System.Collections.Generic;
+using System.Linq;
 using FluentMigrator.Builders.Delete;
 using FluentMigrator.Builders.Delete.Column;
 using FluentMigrator.Builders.Delete.ForeignKey;
@@ -57,7 +58,7 @@ public void CallingColumnAddsDeleteColumnExpressionToContextWithSpecifiedName()
             var root = new DeleteExpressionRoot(contextMock.Object);
             root.Column("Bacon");
 
-            collectionMock.Verify(x => x.Add(It.Is<DeleteColumnExpression>(e => e.ColumnName.Equals("Bacon"))));
+            collectionMock.Verify(x => x.Add(It.Is<DeleteColumnExpression>(e => e.ColumnNames.ElementAt(0).Equals("Bacon"))));
             contextMock.VerifyGet(x => x.Expressions);
         }
 

src/FluentMigrator.Tests/Unit/Expressions/CreateColumnExpressionTests.cs

@@ -18,6 +18,7 @@
 
 using System;
 using System.Data;
+using System.Linq;
 using FluentMigrator.Expressions;
 using FluentMigrator.Infrastructure;
 using FluentMigrator.Model;
@@ -75,7 +76,7 @@ public void ReverseSetsTableNameAndColumnNameOnGeneratedExpression()
             var expression = new CreateColumnExpression { TableName = "Bacon", Column = { Name = "BaconId" } };
             var reverse = expression.Reverse() as DeleteColumnExpression;
             reverse.TableName.ShouldBe("Bacon");
-            reverse.ColumnName.ShouldBe("BaconId");
+            reverse.ColumnNames.ElementAt(0).ShouldBe("BaconId");
         }
 
         [Test]

src/FluentMigrator.Tests/Unit/Expressions/DeleteColumnExpressionTests.cs

@@ -55,23 +55,31 @@ public void ErrorIsNotReturnedWhenTableNameIsNotNullEmptyString()
         [Test]
         public void ErrorIsReturnedWhenColumnNameIsNull()
         {
-            var expression = new DeleteColumnExpression { ColumnName = null };
+            var expression = new DeleteColumnExpression { ColumnNames = {null} };
             var errors = ValidationHelper.CollectErrors(expression);
             errors.ShouldContain(ErrorMessages.ColumnNameCannotBeNullOrEmpty);
         }
 
         [Test]
         public void ErrorIsReturnedWhenColumnNameIsEmptyString()
         {
-            var expression = new DeleteColumnExpression { ColumnName = String.Empty };
+            var expression = new DeleteColumnExpression { ColumnNames = {String.Empty} };
             var errors = ValidationHelper.CollectErrors(expression);
             errors.ShouldContain(ErrorMessages.ColumnNameCannotBeNullOrEmpty);
         }
 
+        [Test]
+        public void ErrorIsReturnedWhenColumnIsSpecifiedMultipleTimes() 
+        {
+            var expression = new DeleteColumnExpression { ColumnNames = { "Bacon", "Bacon" } };
+            var errors = ValidationHelper.CollectErrors(expression);
+            errors.ShouldContain(ErrorMessages.ColumnNamesMustBeUnique);
+        }
+
         [Test]
         public void ErrorIsNotReturnedWhenColumnNameIsNotNullEmptyString()
         {
-            var expression = new DeleteColumnExpression { ColumnName = "Bacon" };
+            var expression = new DeleteColumnExpression { ColumnNames = {"Bacon"} };
             var errors = ValidationHelper.CollectErrors(expression);
             errors.ShouldNotContain(ErrorMessages.ColumnNameCannotBeNullOrEmpty);
         }
@@ -86,7 +94,7 @@ public void ReverseThrowsException()
         [Test]
         public void ToStringIsDescriptive()
         {
-            var expression = new DeleteColumnExpression { TableName = "Test", ColumnName = "Bacon" };
+            var expression = new DeleteColumnExpression { TableName = "Test", ColumnNames = {"Bacon"} };
             expression.ToString().ShouldBe("DeleteColumn Test Bacon");
         }
     }

src/FluentMigrator.Tests/Unit/Generators/GeneratorTestHelper.cs

@@ -292,7 +292,12 @@ public static DeleteTableExpression GetDeleteTableExpression()
 
         public static DeleteColumnExpression GetDeleteColumnExpression()
         {
-            return new DeleteColumnExpression { TableName = TestTableName1, ColumnName = TestColumnName1 };
+            return GetDeleteColumnExpression(new [] {TestColumnName1});
+        }
+
+        public static DeleteColumnExpression GetDeleteColumnExpression(string[] columns)
+        {
+            return new DeleteColumnExpression { TableName = TestTableName1, ColumnNames = columns };
         }
 
         public static DeleteIndexExpression GetDeleteIndexExpression()

src/FluentMigrator.Tests/Unit/Generators/Jet/JetDropTableTests.cs

@@ -25,6 +25,15 @@ public override void CanDropColumn()
             sql.ShouldBe("ALTER TABLE [TestTable1] DROP COLUMN [TestColumn1]");
         }
 
+        [Test]
+        public void CanDropMultipleColumns()
+        {
+            var expression = GeneratorTestHelper.GetDeleteColumnExpression(new string[] { "TestColumn1", "TestColumn2" });
+
+            string sql = _generator.Generate(expression);
+            sql.ShouldBe("ALTER TABLE [TestTable1] DROP COLUMN [TestColumn1];\r\nALTER TABLE [TestTable1] DROP COLUMN [TestColumn2]");
+        }
+
         [Test]
         public override void CanDropForeignKey()
         {

src/FluentMigrator.Tests/Unit/Generators/MySql/MySqlDropTableTests.cs

@@ -24,6 +24,14 @@ public override void CanDropColumn()
             sql.ShouldBe("ALTER TABLE `TestTable1` DROP COLUMN `TestColumn1`");
         }
 
+        [Test]
+        public void CanDropMultipleColumns()
+        {
+            var expression = GeneratorTestHelper.GetDeleteColumnExpression(new string[] {"TestColumn1", "TestColumn2"});
+            var sql = _generator.Generate(expression);
+            sql.ShouldBe("ALTER TABLE `TestTable1` DROP COLUMN `TestColumn1`;\r\nALTER TABLE `TestTable1` DROP COLUMN `TestColumn2`");
+        }
+
         [Test]
         public override void CanDropForeignKey()
         {

src/FluentMigrator.Tests/Unit/Generators/Oracle/OracleDropTableTests.cs

@@ -24,6 +24,14 @@ public override void CanDropColumn()
             sql.ShouldBe("ALTER TABLE TestTable1 DROP COLUMN TestColumn1");
         }
 
+        [Test]
+        public void CanDropMultipleColumns()
+        {
+            var expression = GeneratorTestHelper.GetDeleteColumnExpression(new string[] {"TestColumn1", "TestColumn2"});
+            string sql = _generator.Generate(expression);
+            sql.ShouldBe("ALTER TABLE TestTable1 DROP COLUMN TestColumn1;\r\nALTER TABLE TestTable1 DROP COLUMN TestColumn2");
+        }
+
         [Test]
         public override void CanDropForeignKey()
         {

src/FluentMigrator.Tests/Unit/Generators/Postgres/PostgresGeneratorTests.cs

@@ -157,12 +157,25 @@ public void CanDropColumn()
 
             var expression = new DeleteColumnExpression();
             expression.TableName = tableName;
-            expression.ColumnName = columnName;
+            expression.ColumnNames.Add(columnName);
 
             string sql = generator.Generate(expression);
             sql.ShouldBe("ALTER TABLE \"public\".\"NewTable\" DROP COLUMN \"NewColumn\"");
         }
 
+        [Test]
+        public void CanDropMultipleColumns()
+        {
+            var expression = new DeleteColumnExpression();
+            expression.TableName = "NewTable";
+            expression.ColumnNames.Add("NewColumn");
+            expression.ColumnNames.Add("OtherColumn");
+
+            string sql = generator.Generate(expression);
+            sql.ShouldBe("ALTER TABLE \"public\".\"NewTable\" DROP COLUMN \"NewColumn\";\r\n" + 
+                "ALTER TABLE \"public\".\"NewTable\" DROP COLUMN \"OtherColumn\"");
+        }
+
         [Test]
         public void CanAddColumn()
         {

src/FluentMigrator.Tests/Unit/Generators/SQLite/SQLiteDropTableTests.cs

@@ -25,6 +25,14 @@ public override void CanDropColumn()
             sql.ShouldBe(String.Empty); //because sqlite doesnt support removing columns
         }
 
+        [Test]
+        public void CanDropMultipleColumns()
+        {
+            var expression = GeneratorTestHelper.GetDeleteColumnExpression(new string[] {"TestColumn1", "TestColumn2"});
+            string sql = _generator.Generate(expression);
+            sql.ShouldBe(String.Empty); //because sqlite doesnt support removing columns
+        }
+
         [Test]
         public override void CanDropForeignKey()
         {