Cannot add or update a child row: a foreign key constraint fails
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Tom
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Published on 2011-02-15T15:11:01Z
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2011/02/15
15:25 UTC
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mysql
table 1
+----------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+----------------+
| UserID | int(11) | NO | PRI | NULL | auto_increment |
| Password | varchar(20) | NO | | | |
| Username | varchar(25) | NO | | | |
| Email | varchar(60) | NO | | | |
+----------+-------------+------+-----+---------+----------------+
table2
+------------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------------+--------------+------+-----+---------+----------------+
| UserID | int(11) | NO | MUL | | |
| PostID | int(11) | NO | PRI | NULL | auto_increment |
| Title | varchar(50) | NO | | | |
| Summary | varchar(500) | NO | | | |
+------------------+--------------+------+-----+---------+----------------+
com.mysql.jdbc.exceptions.MySQLIntegrityConstraintViolationException:
Cannot add or update a child row: a foreign key constraint fails (myapp/table2, CONSTRAINT table2_ibfk_1 FOREIGN KEY (UserID) REFERENCES table1 (UserID))
What have I done wrong? I read this: http://www.w3schools.com/Sql/sql_foreignkey.asp and i don't see whats wrong. :S
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