HINT: For debugging reasons, you may comment out the "-select raise(ignore)" line. Īdditionally, everything contained within the trigger will also consider updates performed recently, by the code itself (unlike a global update which first prepares the set to update and then executes, without considering the results of its proper update. You will notice that this trick is extremely fast, much faster than update with a where clause. Table 1 has 50,000 rows and Table 2 has 25 million rows. Update real_table set val1 = new.val1, val2 = new.val2 where id = new.id itemID Qty - 1 10 2 10 3 10 userbasket table to keep users' basket data. Here is the code example: drop table if exists dummy Ĭreate temporary table dummy (id number, val1, val2) Ĭreate trigger dummy_ins before insert on dummy I am using SQLite to update mulipte rows, but it does not work. Instead of updating real_table, INSERT into DUMMY. In SQLite I need to update row counts of a related table. The update is a SQL keyword and it falls under Data Manipulation Language (DML), as the name suggests it is used to manipulate the data. Then formulate your query, however complex, containing joins, aggregates, withs. We can update all the rows in the database or some values with the help of conditions. Details If the UPDATE statement does not have a WHERE clause, all rows in the table are modified by the UPDATE. Here's a TRICK for complex updates: use a trigger on a dummy temporary table which never receives any records. An UPDATE statement is used to modify a subset of the values stored in zero or more rows of the database table identified by the qualified-table-name specified as part of the UPDATE statement.
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