what is Correct syntax for executing sql syntax?

Question

String ag ="ALTER TABLE QUESTION"+
            "(ADD  FOREIGN KEY (a_status) REFERENCES ANSWER(a_status))";

                      stmt.executeUpdate(ag);

Error message: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FOREIGN KEY (a_status) REFERENCES ANSWER(a_status))' at line 1

possible duplicate of [Add Foreign Key to existing table](http://stackoverflow.com/questions/10028214/add-foreign-key-to-existing-table) — ughai, May 28 '15 at 06:33

score 0 · Answer 1 · answered May 28 '15 at 06:33

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This should be correct. See the offical documentation:

String ag ="ALTER TABLE QUESTION ADD FOREIGN KEY (a_status) REFERENCES ANSWER(a_status)";

answered May 28 '15 at 06:33

Jens

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Vishal · Answer 2 · 2015-05-28T13:36:38.640

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String ag ="ALTER TABLE QUESTION ADD CONSTRAINT (question_answer_ibfk1) FOREIGN KEY (a_status) REFERENCES ANSWER(a_status)";

In general

ALTER TABLE Child_tblName
ADD CONSTRAINT 'give any name to the foreign key generally I do Child_tblName_Parent_tblName_ibfk_number' FOREIGN KEY ('Child_tblName's Column') REFERENCES Parent_tblName('Parent_tblName's Column')

edited May 28 '15 at 13:36

answered May 28 '15 at 07:05

Vishal

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thank you sir **@Ole Albers!** for adding the good CodeBlock view for better readability , I am new to stackoverflow so learning these edition things. – Vishal May 28 '15 at 07:16

score 0 · Answer 3 · answered May 28 '15 at 07:19

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String ag ="ALTER TABLE QUESTION ADD CONSTRAINT (question_answer_fk1) FOREIGN KEY (a_status) REFERENCES ANSWER(a_status)";

Also you can have more condition specific to add:

ON DELETE SET NULL/CASCADE
ON UPDATE SET NULL

answered May 28 '15 at 07:19

Sagar Panda

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what is Correct syntax for executing sql syntax?

3 Answers3