AI代码解释 ---Table structureforstudent---DROPTABLEIFEXISTS`student`;CREATETABLE`student`(`id`int(11)NOTNULLAUTO_INCREMENTCOMMENT'id',`sno`varchar(20)CHARACTERSETutf8COLLATEutf8_unicode_ciNULLDEFAULTNULLCOMMENT'学号',`sname`varchar(10)CHARACTERSETutf8COLLATEutf8_unicode_ciNULLDEFAULTNULLCOMMENT'学生...
Since we can specify constraints on a table, there needs to be a way to remove this constraint as well. In SQL, this is done via the ALTER TABLE statement. The SQL syntax to remove a constraint from a table is, ALTER TABLE "table_name" DROP [CONSTRAINT|INDEX] "CONSTRAINT_NAME";...
The error message “Could not drop object ‘production.brands’ because it is referenced by a FOREIGN KEY constraint. (Microsoft SQL Server, Error: 3726)” is telling us why the table cannot be dropped. In this case we would need to step through dropping the constraints then dropping the t...
2 DROP PRIMARY KEY CASCADE; --删除后可以看到不存在tb_dept主键约束及tb_cons2外键的记录 SQL> SELECT constraint_name,constraint_type,table_name,status,deferrable,validated 2 FROM user_constraints 3 ORDER BY table_name; CONSTRAINT_NAME C TABLE_NAME STATUS DEFERRABLE VALIDATED --- - --- --- --...
Removes one or more table definitions and all data, indexes, triggers, constraints, and permission specifications for those tables. Any view or stored procedure that references the dropped table must be explicitly dropped by using DROP VIEW or DROP PROCEDURE. To report the dependencies on a table...
TheALTER TABLEstatement is also used to add and drop various constraints on an existing table. ALTER TABLE - ADD Column To add a column in a table, use the following syntax: ALTERTABLEtable_name ADDcolumn_name datatype; The following SQL adds an "Email" column to the "Customers" table:...
ALL_SPARSE_COLUMNS <table_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] ( column_name [ ASC | DESC ] [ ,... n ] ) [ WITH FILLFACTOR = fillfactor | WITH ( <index_option> [ ,... n ] ) ] [ ON { partition_scheme_...
The SQL DROP TABLE statement is a Data Definition Language (DDL) command that is used to remove a table's definition, and its data, indexes, triggers, constraints and permission specifications (if any).Note − You should be very careful while using this command because once a table is ...
DROP Table [dbname][Schema name]table1,table2….table n; While the DROP command eliminates designated schema pieces like relations, tables, constraints, or the entire schema. The DELETE command removes a few or all tuples/records from a relation/table. Only those tuples that meet the WHERE...
ALTER TABLE [dbo].[Products] DROP COLUMN [ProductFeedback], [ProductLaunchDate] GO 1. 2. 3. 4. (SQL DELETE column contains CHECK constraints) We use CHECK constraints to limit the value range in a column. Suppose you have a column having CHECK constrains on it. ...