Add a Unique ConstraintWrite a SQL query to add a unique constraint to a column in an existing table.Solution:-- Add a unique constraint to the "Name" column to ensure no duplicate names. ALTER TABLE Employees -- Specify the table to modify. ADD CONSTRAINT UC_Name UNIQUE (Name)...
ALTER TABLE 表名称 ADD UNIQUE (列名称) 新增多个列唯一约束: ALTER TABLE 表名称 ADD CONSTRAINT uc_约束名 UNIQUE (列名称,列名称...) 撤销唯一约束: ALTER TABLE 表名称 DROP CONSTRAINT uc_约束名 PRIMARY KEY(主键)更新: 新增主键约束: ALTER TABLE 表名称 ADD PRIMARY KEY (列名称) 新增多个列主键约...
obclient>ALTERTABLEtestADDCOLUMNc4INTEGERFIRST; 设置表test的副本数。 obclient>ALTERTABLEtestSETREPLICA_NUM=2; 为表t1添加外键约束fk1。 obclient>ALTERTABLEt1ADDCONSTRAINTfk1FOREIGNKEY(c3)REFERENCESt2(c1); 删除t1表的外键约束fk1。 obclient>ALTERTABLEt1DROPFOREIGNKEYfk1; ...
ALTER TABLE table-name 1ADDCOLUMNcolumn-definitionALTERCOLUMNcolumn-alterationRENAME COLUMNsource-column-nameTOtarget-column-nameDROPCOLUMNcolumn-nameRESTRICTADD PERIODFORperiod-definitionADDunique-constraintreferential-constraintcheck-constraint4DROPRPRIMARY KEYUNIQUEFOREIGN KEYCHECKCONSTRAINTconstraint-nameADD PARTITIO...
删除分区数据时,请尽量避免该分区上存在活动的事务或查询,否则可能会导致 SQL 语句报错,或者一些异常情况。 RENAME [TO] table_name表重命名。 RENAME {INDEX | KEY}重命名索引或键。 DROP [TABLEGROUP]删除表组。 DROP [FOREIGN KEY]删除外键。 [SET] table_option设置表级属性,可选以下参数: ...
ALTER TABLE nested_skill_table ADD UNIQUE (a); The following statement alters the storage table for a nested table of REF values to specify that the REF is scoped: CREATE TYPE emp_t AS OBJECT (eno number, ename char(31)); CREATE TYPE emps_t AS TABLE OF REF emp_t; CREATE TABLE emp...
Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance SQL database in Microsoft Fabric Specifies a set of options that can be applied to an index that is part of a constraint definition that is created by using ALTER TABLE. For a complete description of index options, see ...
{ CHECK | NOCHECK } ] | ADD { <column_definition> | <computed_column_definition> | <table_constraint> | <column_set_definition> } [ ,...n ] | [ system_start_time_column_name datetime2 GENERATED ALWAYS AS ROW START [ HIDDEN ] [ NOT NULL ] [ CONSTRAINT constraint_name ] DEFAULT ...
S はtyped-view-name2 のタイプを表します (SQLSTATE 428DM)。値が typed-view-name2 の既存行を実際に参照していることを確認するための、 column-name のデフォルト値の検査は行われません。 CONSTRAINT constraint-name 制約の名前を指定します。制約名 (constraint-name) は、同じ ALTER TABLE ...
{ CHECK | NOCHECK } ] | ADD { <column_definition> | <computed_column_definition> | <table_constraint> | <column_set_definition> } [ ,...n ] | [ system_start_time_column_name datetime2 GENERATED ALWAYS AS ROW START [ HIDDEN ] [ NOT NULL ] [ CONSTRAINT constraint_name ] DEFAULT ...