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DROP TABLE IF EXISTS t1,t2,t3;
CREATE TABLE t1 (id INT NOT NULL, PRIMARY KEY (id)) ENGINE=INNODB;
CREATE TABLE t2 (id INT PRIMARY KEY, t1_id INT, INDEX par_ind (t1_id, id),
FOREIGN KEY (t1_id) REFERENCES t1(id) ON DELETE CASCADE,
FOREIGN KEY (t1_id) REFERENCES t1(id) ON UPDATE CASCADE) ENGINE=INNODB;
CREATE TABLE t3 (id INT PRIMARY KEY, t2_id INT, INDEX par_ind (t2_id),
FOREIGN KEY (id, t2_id) REFERENCES t2(t1_id, id) ON DELETE CASCADE) ENGINE=INNODB;
select * from information_schema.TABLE_CONSTRAINTS where
TABLE_SCHEMA= "test";
CONSTRAINT_CATALOG CONSTRAINT_SCHEMA CONSTRAINT_NAME TABLE_SCHEMA TABLE_NAME CONSTRAINT_TYPE
NULL test PRIMARY test t1 PRIMARY KEY
NULL test PRIMARY test t2 PRIMARY KEY
NULL test t2_ibfk_1 test t2 FOREIGN KEY
NULL test t2_ibfk_2 test t2 FOREIGN KEY
NULL test PRIMARY test t3 PRIMARY KEY
NULL test t3_ibfk_1 test t3 FOREIGN KEY
select * from information_schema.KEY_COLUMN_USAGE where
TABLE_SCHEMA= "test";
CONSTRAINT_CATALOG CONSTRAINT_SCHEMA CONSTRAINT_NAME TABLE_CATALOG TABLE_SCHEMA TABLE_NAME COLUMN_NAME ORDINAL_POSITION POSITION_IN_UNIQUE_CONSTRAINT REFERENCED_TABLE_SCHEMA REFERENCED_TABLE_NAME REFERENCED_COLUMN_NAME
NULL test PRIMARY NULL test t1 id 1 NULL NULL NULL NULL
NULL test PRIMARY NULL test t2 id 1 NULL NULL NULL NULL
NULL test t2_ibfk_1 NULL test t2 t1_id 1 1 test t1 id
NULL test t2_ibfk_2 NULL test t2 t1_id 1 1 test t1 id
NULL test PRIMARY NULL test t3 id 1 NULL NULL NULL NULL
NULL test t3_ibfk_1 NULL test t3 id 1 1 test t2 t1_id
NULL test t3_ibfk_1 NULL test t3 t2_id 2 2 test t2 id
drop table t3, t2, t1;
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