We can also add theUNIQUEconstraint to an existing column using theALTER TABLEcommand. For example, For a Single Column -- add unique constraint to an existing columnALTERTABLECollegesADDUNIQUE(college_id); Here, the SQL command adds theUNIQUEconstraint to thecolleges_idcolumn in the existingColl...
试着做这样的事情：
违反了唯一性约束，所以导致插入不正确。ORACLE违反唯一约束条件解决方法 java代码报错：java.sql.BatchUpdateException: ORA-00001: 违反唯一约束条件 (TTT.table)at oracle.jdbc.driver.DatabaseError.throwBatchUpdateException(DatabaseError.java:629)at oracle.jdbc.driver.OraclePreparedStatement.executeBatch(...
若要暂停、恢复或中止 ALTER TABLE ADD CONSTRAINT 的可恢复表约束操作,请使用 T-SQL 语法 ALTER INDEX (Transact-SQL)。对于可恢复约束,使用现有的 ALTER INDEX ALL 命令。syntaxsql 复制 ALTER INDEX ALL ON { RESUME [WITH (<resumable_index_options>,[...n])] | PAUSE | A...
Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Specifies the properties of a PRIMARY KEY, FOREIGN KEY, UNIQUE, or CHECK constraint that is part of a new column definition added to a table by using ALTER TABLE. Transact-SQL syntax conventions Syntax Syntax for SQL Server...
您必須先重建 (啟用) 索引,才可以啟用參考 PRIMARY KEY 或 UNIQUE 條件約束的 FOREIGN KEY 條件約束。 FOREIGN KEY 條件約束是使用 ALTER TABLE CHECK CONSTRAINT 陳述式來啟用。 當ONLINE 選項設定為 ON 時,將無法重建停用的叢集索引。 當停用或啟用叢集索引,而非叢集索引是停用狀態時,叢集索引動作在停用的非叢集...
[ CONSTRAINT constraint_name ] { [ NULL | NOT NULL ] { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] [ WITH FILLFACTOR =fillfactor ] [ WITH ( index_option [, ...n ] ) ] [ ON { partition_scheme_name (partition_column_name) | filegroup | "default" } ] | [ FOREIGN KEY...
SQL UNIQUE Constraint on ALTER TABLE To create a UNIQUE constraint on the "P_Id" column when the table is already created, use the following SQL: MySQL / SQL Server / Oracle / MS Access: ALTERTABLEPersonsADDUNIQUE(P_Id) To allow naming of a UNIQUE constraint, and for defining a UNIQUE...
Most of you must have come across the pain of adding a not null column with a default value to an existing big table. It takes minutes to add columns. I recently found out that this problem has been resolved in SQL Server 2012. Let’s look into some ways to resolve this in versions...
In Object Explorer, connect to an instance of Database Engine. On the Standard bar, select New Query. Copy and paste the following example into the query window and select Execute. The example creates the table TransactionHistoryArchive4 and creates a unique constraint on the column Transaction...