mysql> ALTER TABLE testalter_tbl MODIFY c CHAR(10); 使用CHANGE 子句, 语法有很大的不同。 在 CHANGE 关键字之后,紧跟着的是你要修改的字段名,然后指定新字段名及类型。尝试如下实例: mysql> ALTER TABLE testalter_tbl CHANGE i j BIGINT; mysql> ALTER TABLE testalter_tbl CHANGE j j INT; ALTER T...
You can add, drop, or modify the columns of an external table. However, for an external table you cannot: Add a LONG, LOB, or object type column or change the datatype of an external table column to any of these datatypes. Add a constraint to an external table. Modify the storage...
ALTERTABLETABLE_NAME MODIFYCOLUMNcolumn_name new_datatype; 以下SQL 语句将 employees 表中的 salary 列的数据类型修改为 DECIMAL(10,2): 实例 ALTERTABLEemployees MODIFYCOLUMNsalaryDECIMAL(10,2); 3. 修改列名 ALTERTABLEtable_name CHANGECOLUMNold_column_name new_column_name datatype; 以下SQL 语句将 emp...
SqlServer.TransactSql.ScriptDom Microsoft.SqlServer.TransactSql.ScriptDom AbortAfterWaitType AcceleratedDatabaseRecoveryDatabaseOption AddAlterFullTextIndexAction AddFileSpec AddMemberAlterRoleAction AddSearchPropertyListAction AddSensitivityClassificationStatement AddSignatureStatement AdHocDataSource AdHocTableReference ...
Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW) Warehouse in Microsoft Fabric Modifies a table definition by altering, adding, or dropping columns and constraints. ALTER TABLE also reassigns and rebuilds partitions, or disabl...
Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW) Warehouse in Microsoft Fabric SQL database in Microsoft Fabric Modifies a table definition by altering, adding, or dropping columns and constraints. ALTER TABLE also reassigns ...
1. Build the 'Alter' script to copy rows into a new table (in clumps of rows) 2. Push code to add a Database Layer between client(s) and the database 3. Push code to augment the Database Layer to handle the effect of the Alter ...
可以通过运行UserDefinedDataType示例脚本来创建程序集ComplexNumber。 有关详细信息,请参阅用户定义类型。 SQL ALTERASSEMBLYComplexNumberFROM'C:\Program Files\Microsoft SQL Server\130\Tools\Samples\1033\Engine\Programmability\CLR\UserDefinedDataType\CS\ComplexNumber\obj\Debug\ComplexNumber.dll' ...
Notice that the DataType of the Salary column is nvarchar. Now let's change it to an int like this. Now save it and see what happens. We will get a warning like this. Basically, it says that we need to drop and re-create the table, but we have some data in this table so if ...
This SQL tutorial explains how to use the SQL ALTER TABLE statement to add a column, modify a column, drop a column, rename a column or rename a table (with lots of clear, concise examples). It is used to add, modify, or drop/delete columns in a table.