SQL query to delete the multiple tables

Question

query to delete multiple(4 to 5) tables in the database using the join condition because tables are having dependency with each other

Brahma Prakash Shukla · Answer

To delete multiple tables in a database with dependencies using join conditions, you need to perform the deletion in the reverse order of their dependencies. Here's an example query that demonstrates how you can achieve this: BEGIN TRANSACTION; -- Start a transaction to ensure atomicity -- Disable foreign key checks SET FOREIGN_KEY_CHECKS = 0; -- Delete data from the dependent tables in reverse order DELETE t1, t2, t3, t4, t5 FROM table5 AS t5 JOIN table4 AS t4 ON t4.id = t5.table4_id JOIN table3 AS t3 ON t3.id = t4.table3_id JOIN table2 AS t2 ON t2.id = t3.table2_id JOIN table1 AS t1 ON t1.id = t2.table1_id; -- Enable foreign key checks SET FOREIGN_KEY_CHECKS = 1; COMMIT; -- Commit the transaction and make the changes permanent In the example above, table5 depends on table4 , which depends on table3 , and so on. By joining the tables in reverse order and specifying the delete operation on all the tables involved, you can delete the data while maintaining referential integrity. Note: The exact query may vary depending on the database management system you are using, as different DBMSs have slightly different syntax. The example above assumes a standard SQL syntax. Make sure to replace table1 , table2 , table3 , table4 , and table5 with the actual names of the tables you want to delete. Also, remember to take proper backups before performing any deletion operations to ensure data safety.

Subarta Ray · Answer

DELETE Table1, Table2, Table3, Table4, Table5 FROM Table1 INNER JOIN Table2 ON Table1.ID = Table2.Table1ID INNER JOIN Table3 ON Table2.ID = Table3.Table2ID INNER JOIN Table4 ON Table3.ID = Table4.Table3ID INNER JOIN Table5 ON Table4.ID = Table5.Table4ID WHERE YourCondition;

Anandu G Nath · Answer

BEGIN TRANSACTION; DELETE t1, t2, t3, t4, t5 FROM Table1 t1 LEFT JOIN Table2 t2 ON t1.ColumnID = t2.ForeignKeyColumnID LEFT JOIN Table3 t3 ON t2.AnotherColumn = t3.YetAnotherColumn LEFT JOIN Table4 t4 ON t3.SomeColumn = t4.SomeForeignKeyColumn LEFT JOIN Table5 t5 ON t4.OtherColumn = t5.SomeOtherColumn WHERE ; COMMIT TRANSACTION;

Jignesh Kumar · Answer

Hello Meghana, You can use below query to delete from 5 different table, Below query delete reocords from all five table where t1 table with Id =1 DELETE t1, t2, t3, t4, t5 FROM MyTable t1 JOIN MyTable2 t2 ON t1.id = t2.table1_id JOIN MyTable3 t3 ON t1.id = t3.table1_id JOIN MyTable4 t4 ON t2.id = t4.table2_id JOIN MyTable5 t5 ON t3.id = t5.table3_id WHERE t1.id = 1;

Nitin Sontakke · Answer

Which database system is this? Oracle / SQL Server / PostgreSQL? Because I haven't so far seen this syntax. @Arvind, have you tested the code snippent you have provided? @Meghana, you can delete data from tables having dependency (I hope you mean PK / FK constraints) by just deleting the record(s) from main table. While defining constraint, you have a choice to mention that you want to delete record(s) from child table(s) when record(s) deleted from parent table. See CASCADE keyword. Hope it helps!

Janarthanan Selvaraj · Answer

To delete multiple tables in a database using join conditions due to dependencies, you need to carefully plan the order of deletion to avoid violating referential integrity constraints. Here's a general approach you can follow: Identify the tables and their dependencies: Determine the order in which tables should be deleted based on their dependencies. A table with foreign key constraints should be deleted after the table it references. Start with the tables that have no dependencies: Begin by deleting the tables that have no foreign key constraints. These tables can be deleted without affecting other tables. Delete tables with dependent foreign keys: Move on to tables that have foreign keys referencing other tables. Delete these tables after deleting the tables they depend on. Use joins to delete rows: When deleting tables with dependencies, use join conditions to ensure that only the relevant rows are deleted. You can use the DELETE statement with JOIN clauses to delete rows from multiple tables in a single query. DELETE t1, t2, t3, t4, t5 FROM table1 AS t1 JOIN table2 AS t2 ON t2.table1_id = t1.id JOIN table3 AS t3 ON t3.table2_id = t2.id JOIN table4 AS t4 ON t4.table3_id = t3.id JOIN table5 AS t5 ON t5.table4_id = t4.id WHERE ;

Aravind Govindaraj · Answer

Please find the code snippet for the same DELETE t1, t2, t3, t4, t5 FROM table1 t1 JOIN table2 t2 ON t1.column = t2.column JOIN table3 t3 ON t1.column = t3.column JOIN table4 t4 ON t1.column = t4.column JOIN table5 t5 ON t1.column = t5.column WHERE ;