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POHow to delete corresponding row using ON DELETE CASCADE
 

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  1. POHow to delete corresponding row using ON DELETE CASCADE
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    <p>I have 2 Tables, one known as "Image" Table, other known as "Image_Question" Table. Below is what the 2 tables could look like:</p> <p>Image Table:</p> <pre><code>ImageId ImageFile 01 picture/cat.png 02 picture/cat_2.png 03 picture/dog.png </code></pre> <p>Image_Question Table:</p> <pre><code>ImageId SessionId QuestionId 01 ADS 3 02 FTG 7 03 JJK 1 </code></pre> <p>What my question is that in SQL how do I write it so that ImageId's from both tables are linked together so that lets say I delete row from Image Table where ImageId = 01, that the ImageId = 01 (corresponding row) from the Image_Question Table is also deleted. </p> <p>I tried the code below but it did not work:</p> <pre><code>ALTER TABLE Image_Question ADD CONSTRAINT FK_ImageId FOREIGN KEY (ImageId) REFERENCES Image (ImageId) ON DELETE CASCADE; </code></pre> <p>UPDATE:</p> <p>SHOW IMAGE TABLE:</p> <pre><code>CREATE TABLE `Image` ( `ImageId` int(10) NOT NULL AUTO_INCREMENT, `ImageFile` varchar(250) NOT NULL, PRIMARY KEY (`ImageId`) ) ENGINE=MyISAM AUTO_INCREMENT=399 DEFAULT CHARSET=utf8 </code></pre> <p>SHOW IMAGE_QUESTION TABLE:</p> <pre><code>CREATE TABLE `Image_Question` ( `ImageQuestionId` int(10) NOT NULL AUTO_INCREMENT, `ImageId` int(10) NOT NULL, `SessionId` varchar(10) NOT NULL, `QuestionId` int(5) NOT NULL, PRIMARY KEY (`ImageQuestionId`), KEY `QuestionId` (`QuestionId`), KEY `SessionId` (`SessionId`), KEY `fk_imagequestionid` (`ImageId`) ) ENGINE=MyISAM AUTO_INCREMENT=4 DEFAULT CHARSET=utf8 </code></pre>
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    1. USuser1701484
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    1. COWhat do you mean it didn't work? Did it give an error? Did you try deleting from the image_question table and it didn't delete from image table?
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      1. USSteven Mastandrea
    2. COThe deletion of data did not work?? OR ALTER TABLE - addition of key did not work
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      1. USA Developer
    3. COThe syntax of the query was fine, but when I delete a row from either table, it did not delete the corresponding row in the other table
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      1. USuser1701484
 

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