SQL语言与数据库操作技术大全3.5.3 删除列——DROP COLUMN第3章数据库与表的操作在关系数据库中,数据都是存储在表中的。在上一章已经讨论了在SQLServer2005中使用ManagementStudio创建数据库和表。在本章将主要介绍使用SQL对数据库和表进
[DROPCOLUMNcolumn_name2]; 在上面语法中, table_name是包含要删除列的表名称。 column_name1,column_name2是将要删除的列。 MySQL和PostgreSQL支持上述语法。 Oracle和SQL Server的语法略有不同: ALTERTABLEtable_nameDROPCOLUMNcolumn_name1, [column_name2]; 2. SQL DROP COLUMN示例 以下语句为演示创建一个名...
Transact-SQL syntax conventionsSyntaxsyntaxsql Copy sp_repldropcolumn [ @source_object = ] N'source_object' , [ @column = ] N'column' [ , [ @from_agent = ] from_agent ] [ , [ @schema_change_script = ] N'schema_change_script' ] [ , [ @force_invalidate_snapshot ...
The following SQL deletes the "ContactName" column from the "Customers" table:Example ALTER TABLE CustomersDROP COLUMN ContactName; Try it Yourself » ❮ SQL Keywords Reference Track your progress - it's free! Log in Sign Up COLOR PICKER PLUS...
Transact-SQL 语法约定 语法 复制 sp_repldropcolumn [ @source_object = ] 'source_object', [ @column = ] 'column' [ , [ @from_agent = ] from_agent ] [ , [ @schema_change_script = ] 'schema_change_script' ] [ , [ @force_invalidate_snapshot = ] force_invalidate_snapshot ] [...
SparseColumnOption SpatialIndexingSchemeType SpatialIndexOption SpatialIndexRegularOption Sql100ScriptGenerator Sql110ScriptGenerator Sql120ScriptGenerator Sql130ScriptGenerator Sql140ScriptGenerator Sql150ScriptGenerator Sql160ScriptGenerator Sql80ScriptGenerator Sql90ScriptGenerator SqlCommandIdentifier SqlDataTypeOp...
Learn more about the Microsoft.SqlServer.TransactSql.ScriptDom.DropIndexStatement.DropIndexStatement in the Microsoft.SqlServer.TransactSql.ScriptDom namespace.
DROP SERVICE (Transact-SQL) DROP SIGNATURE (Transact-SQL) DROP STATISTICS (Transact-SQL) DROP SYMMETRIC KEY (Transact-SQL) DROP SYNONYM (Transact-SQL) DROP TABLE (Transact-SQL) DROP TRIGGER (Transact-SQL) DROP TYPE (Transact-SQL) DROP USER (Transact-SQL) ...
SparseColumnOption SpatialIndexingSchemeType SpatialIndexOption SpatialIndexRegularOption Sql100ScriptGenerator Sql110ScriptGenerator Sql120ScriptGenerator Sql130ScriptGenerator Sql140ScriptGenerator Sql150ScriptGenerator Sql160ScriptGenerator Sql80ScriptGenerator Sql90ScriptGenerator SqlCommandIdentifier SqlDataTy...
0 Warnings: 0 mysql> update t set b='a' where a='999999999999'; Query OK, 0 rows affected (1.14 sec) Rows matched: 0 Changed: 0 Warnings: 0 So, SELECT is obviously optimized differently than UPDATE in this case. Workaround is to use proper data type in WHERE (same as column has...