columnN datatype,PRIMARYKEY(oneormore columns ) ); SQL DROP TABLE语句 DROPTABLEtable_name; SQL CREATE INDEX语句 CREATEUNIQUEINDEX index_nameONtable_name ( column1, column2,...columnN); SQL DROP INDEX语句 ALTERTABLEtable_nameDROPINDEX index_name; SQL DESC语句 DESCtable_name; SQL TRUNCATE TAB...
UPDATE table1 SET column1 =(SELECT column FROM table2 [WHERE condition]) WHERE table1.column2= value; 注:若不加where条件则是更新表中的所有数据, 故执行没有where子句的update要慎重再慎重。 实例: UPDATE tb_bookcase SET name= (SELECT bookname FROM tb_bookinfo WHERE tb_bookinfo.type =tb_bookc...
syntaxsql Copy -- Syntax for Azure Synapse Analytics and Microsoft Fabric [ WITH <common_table_expression> [ ,...n ] ] UPDATE [ database_name . [ schema_name ] . | schema_name . ] table_name SET { column_name = { expression | NULL } } [ ,...n ] FROM [ database_name ....
For more information about the syntax of a literal-row value, see the Literal Row segment in theIBM Informix Guide to SQL: Syntax. To represent literal values for a row-type column, you specify a literal-row value. You create a literal-row value or a named or unnamed row type, introduc...
column 要为INSERT 或 UPDATE 操作测试的列的名称。 由于表名是在触发器的 ON 子句中指定的,因此不要在列名前包含表名。 列可以是 SQL Server 支持的任何数据类型。 但是,计算列不能用于此上下文。 返回类型 Boolean 备注 UPDATE() 返回 TRUE,不考虑 INSERT 或 UPDATE 尝试是否成功。
For more information, seeCompound Operators (Transact-SQL). udt_column_name Is a user-defined type column. property_name | field_name Is a public property or public data member of a user-defined type. The expression supplying the value must be implicitly convertible to the type of the proper...
Sometimes we need to change the data type of a column. To do this, we use the ALTER TABLE Modify Column command. For Oracle and MySQL, the SQL syntax for ALTER TABLE Modify Column is, ALTER TABLE "table_name" MODIFY "column_name" "New Data Type";For SQL Server, the syntax is, ALT...
UPDATE table_1 SET column_1 = ... FROM table_1 AS alias_1, table_2 AS alias_2 WHERE ... FROM 子句中 table_1 的每个实例都有一个相关名,用于表明 table_1 本身自连。但是,UPDATE 语句无法指定要更新哪些构成自连接的行。可按照如下方法在 UPDATE 语句中指定相关名来更正此问题: UPDATE table_1...
2.为ColumnA列添加注释: exec sp_addextendedproperty @name=N'MS_Description', @value=N'列A的注释', @level0type=N'SCHEMA', @level0name=N'dbo', @level1type=N'TABLE', @level1name=N'TestTable', @level2type=N'COLUMN', @level2name=N'ColumnA' ...
EntityTableSqlGenerator.UpdateTableColumn 方法 参考 反馈 定义 命名空间: Microsoft.Azure.Mobile.Server.Tables 程序集: Microsoft.Azure.Mobile.Server.Entity.dll 包: Microsoft.Azure.Mobile.Server.Entity v2.0.3 C# 复制 protected virtual void UpdateTableColumn (System.Data.Entity.Migrations...