foreign key field access

\mysql\problem\pic\02.jpgThen see the table involving the foreign key has jbpm4_variable, Jbpm4_execution, jbpm4_swimlane three tables, then clear the three table data can be. Mysql> Delete from jbpm4_variable;Query OK, 1404 rows affected (0.03 sec)mysql> Delete Fromjbpm4_swimlane;Query OK, rows affected (0.03 sec)Mysql> Delete from jbpm4_execution; # Here the error is because the table itself

To add a PRIMARY KEY constraint:ALTER TABLE ga_airline ADD CONSTRAINT pk_airline_id PRIMARY KEY (airline_id);There are three types of foreign KEY constraints:1. Normal FOREIGN KEY constraint (cannot delete parent table record if t

FOREIGN KEY constraintsSyntax: ALTER TABLE from table add [constraint] [foreign key name] foreign key (from table foreign key

Foreign database key, databaseForeign key Create: Method 1: when creating a table, use foreign key (field name) references table name (primary key ); Method 2: add

is not NULL,... Field definition ...}; Set Index To set a foreign key, the corresponding two fields must be indexed (index) in the reference table (referencing table, PC tables) and referenced tables (referenced table, parts tables). For parts table: ALTER TABLE Parts ADD INDEX Idx_model (model); To add an index to the Parts table, the index is built

A foreign key specifies that the value of a column (or a group of columns) must conform to the values of some rows in another table. We say this is to maintain the referential integrity of the associated table.In the graphical interface, the Foreign key tab simply clicks on the Outer

Mysql foreign key creation problem mysql foreign key creation error 150 Mysql error: error Code: 1005. can't create table 'joblog. SC '(errno: 150) create table SC (id int (10) unsigned not null auto_increment comment 'id', Sno int (10) unsigned not null default '0' comment 'student ID ', Cno int (10) unsigned not null

You need to delete the foreign key and primary key first, and store data by creating temporary fields (to reserve the customer's original data ), finally, re-establish the primary key and foreign key 1. Delete the relationship bet

Label:If Table A's primary key is a field in table B, the field is called the Foreign key of Table B, table A is called the primary table, and table B is called from the table. The foreign key