ALTER命令的基本语法因数据库管理系统(DBMS)而异,但一般都遵循相似的结构。在SQL Server和MySQL中,基本语法如下: ALTER TABLE table_name ADD column_name datatype; ALTER TABLE table_name DROP COLUMN column_name; ALTER TABLE table_name MODIFY COLUMN column_name datatype; ALTER TABLE table_name RENAME T...
ADD COLUMN new_column_name datatype; 以下SQL 语句在 employees 表中添加了一个名为 birth_date 的日期列: 实例 ALTERTABLEemployees ADDCOLUMNbirth_dateDATE; 2. 修改列的数据类型 实例 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...
ALTERTABLEtable_nameADDCOLUMNnew_column_name datatype; 以下SQL 语句在 employees 表中添加了一个名为 birth_date 的日期列: 实例 ALTERTABLEemployees ADDCOLUMNbirth_dateDATE; 2. 修改列的数据类型 实例 ALTERTABLETABLE_NAME MODIFYCOLUMNcolumn_name new_datatype; 以下SQL 语句将 employees 表中的 salary 列...
The data type of the column. C# 複製 public Microsoft.SqlServer.TransactSql.ScriptDom.DataTypeReference DataType { get; set; } Property Value DataTypeReference Applies to 產品版本 Microsoft.SQLServer.DacFx 140.3881.1, 150.18208.0, 160.2004021.0, 161.6374.0, 161 本文...
ALTERTABLEtable_nameALTERCOLUMNcolumn_name TYPE datatype; 给表中某列添加 NOT NULL 约束,语法如下: ALTERTABLEtable_name MODIFY column_name datatypeNOTNULL; 给表中某列 ADD UNIQUE CONSTRAINT( 添加 UNIQUE 约束),语法如下: ALTERTABLEtable_nameADDCONSTRAINTMyUniqueConstraintUNIQUE(column1, column2...);...
SQL Server: EXECsp_rename'table_name.old_name','new_name','COLUMN'; ALTER TABLE - ALTER/MODIFY DATATYPE To change the data type of a column in a table, use the following syntax: SQL Server / MS Access: ALTERTABLEtable_name ALTERCOLUMNcolumn_name datatype; ...
Microsoft.SqlServer.TransactSql.ScriptDom Suche Microsoft.SqlServer.TransactSql.ScriptDom Microsoft.SqlServer.TransactSql.ScriptDom AbortAfterWaitType AcceleratedDatabaseRecoveryDatabaseOption AddAlterFullTextIndexAction AddFileSpec AddMemberAlterRoleAction AddSearchPropertyListAction AddSensitivityClassificationStatemen...
The option on the column. The DataType has to be null for this to be AddRowguidcol or DropRowguidcol. (?)PERSISTED used only in 2005"
The option on the column. The DataType has to be null for this to be AddRowguidcol or DropRowguidcol. (?)PERSISTED used only in 2005"
Export the CLOB and SQL NCHAR datatype columns. Drop the tables containing the CLOB and SQL NCHAR columns. Use ALTER DATABASE statements to change the character set and national character set. Reimport the CLOB and SQL NCHAR columns. Restrictions: You must have SYSDBA system privilege,...