Search results
11 wrz 2012 · The following query gives the list of all the primary keys in the given database. SELECT DISTINCT TABLE_NAME ,column_name FROM INFORMATION_SCHEMA.key_column_usage WHERE TABLE_SCHEMA IN ('*your_db_name*');
14 paź 2008 · select concat(table_name, '.', column_name) as 'foreign key', concat(referenced_table_name, '.', referenced_column_name) as 'references', constraint_name as 'constraint name' from information_schema.key_column_usage where referenced_table_name is not null and table_schema = 'database_name';
21 mar 2024 · Below are five ways to get the primary key column/s from an existing table in MySQL. The SHOW KEYS Statement. In MySQL we can use the SHOW KEYS statement to get the primary key for a given table: SHOW KEYS FROM Person . WHERE Key_name = 'PRIMARY'; Example result:
24 maj 2015 · Firstly, find out your FOREIGN KEY constraint name in this way: SELECT TABLE_NAME, COLUMN_NAME, CONSTRAINT_NAME, -- <<-- the one you want! REFERENCED_TABLE_NAME, REFERENCED_COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE REFERENCED_TABLE_NAME = 'My_Table';
The PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values. A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).
30 lip 2019 · To get the primary key of a table, you can use the show command. The syntax is as follows −. SHOW INDEX FROM yourDatebaseName.yourTableName WHERE Key_name = 'PRIMARY'; Suppose, we have a table with two primary keys; one of them is “Id” and second is “RollNum". The query for a table is as follows −.
The FOREIGN KEY constraint is used to prevent actions that would destroy links between tables. A FOREIGN KEY is a field (or collection of fields) in one table, that refers to the PRIMARY KEY in another table.
