{"id":436,"date":"2017-05-17T19:42:23","date_gmt":"2017-05-17T19:42:23","guid":{"rendered":"http:\/\/stackofcodes.in\/?p=429"},"modified":"2017-05-17T19:42:23","modified_gmt":"2017-05-17T19:42:23","slug":"sql-delete-cascade-sql","status":"publish","type":"post","link":"https:\/\/www.chandansharma.co.in\/blog\/sql-delete-cascade-sql\/","title":{"rendered":"Sql-. On delete Cascade in sql"},"content":{"rendered":"
#ON DELETE CASCADE IN SQL\n\nCascade will work when you delete something on table Courses. Any record on table BookCourses that has reference to table Courses will also be deleted.\n\nBut when you try to delete on table BookCourses only the table itself is affected and not on the Courses\n\nfollow-up question: why do you have CourseID on table Category?\n\nMaybe you should restructure your schema into this,\n\nCREATE TABLE Categories\u00a0\n(\n\u00a0 Code CHAR(4) NOT NULL PRIMARY KEY,\n\n\u00a0 CategoryName VARCHAR(63) NOT NULL UNIQUE\n\n);\n\nCREATE TABLE Courses\u00a0\n(\n\u00a0 CourseID INT NOT NULL PRIMARY KEY,\n\n\u00a0 BookID INT NOT NULL,\n\n\u00a0 CatCode CHAR(4) NOT NULL,\n\n\u00a0 CourseNum CHAR(3) NOT NULL,\n\n\u00a0 CourseSec CHAR(1) NOT NULL,\n\n);\n\nALTER TABLE Courses\nADD FOREIGN KEY (CatCode)\nREFERENCES Categories(Code)\nON DELETE CASCADE;<\/pre>\n","protected":false},"excerpt":{"rendered":"
#ON DELETE CASCADE IN SQL Cascade will work when you delete something on table Courses. Any record on table BookCourses that has reference to table … <\/p>\n
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