Subquery can be used in conjunction with the DELETE statement like with any other statements mentioned above.įollowing example deletes records from COMPANY table for all the customers whose AGE is greater than or equal to 27. This would impact two rows and finally COMPANY table would have the following records − WHERE AGE IN (SELECT AGE FROM COMPANY_BKP Either single or multiple columns in a table can be updated when using a subquery with the UPDATE statement.Īssuming, we have COMPANY_BKP table available which is a backup of COMPANY table.įollowing example updates SALARY by 0.50 times in COMPANY table for all the customers, whose AGE is greater than or equal to 27. The subquery can be used in conjunction with the UPDATE statement. To copy the complete COMPANY table into COMPANY_BKP, following is the syntax − INSERT INTO table_name ) ]Ĭonsider a table COMPANY_BKP with similar structure as COMPANY table and can be created using the same CREATE TABLE using COMPANY_BKP as the table name. The selected data in the subquery can be modified with any of the character, date, or number functions.įollowing is the basic syntax is as follows − The INSERT statement uses the data returned from the subquery to insert into another table. Subqueries can also be used with INSERT statements. Subqueries can be used with the SELECT, INSERT, UPDATE, and DELETE statements along with the operators such as =,, >=, SELECT * Only one table is involved in the self-join. The self-join compares values of the same or different columns in the same table. update update MyTable set vala (select x.vala from MyTable x where x.snapshotid 1 and x.objec. Because you cannot refer to the same table more than one in a query, you need to use a table alias to assign the table a different name when you use self-join. HINT: For debugging reasons, you may comment out the "-select raise(ignore)" line.A Subquery or Inner query or Nested query is a query within another SQLite query and embedded within the WHERE clause.Ī subquery is used to return data that will be used in the main query as a condition to further restrict the data to be retrieved. update update MyTable set vala src.vala, valb src.valb, valc src.valc from (select from MyTable where snapshotid 1) as src where MyTable.objectid src.objectid and MyTable.snapshotid 2 2. The SQLite UPDATE command can update more than one row, but all of the rows must be part of the same table. 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. What is UPDATE statement in SQLite Use the statement UPDATE to modify the table Replace the tablename with the name of a table in which modifications are. Update real_table set val1 = new.val1, val2 = new.val2 where id = new.id Updating records based on values in another table table1 SET lumn1 ( SELECT lumn1 FROM table2 WHERE lumn2 lumn2). 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 Instead of updating real_table, INSERT into DUMMY. Then formulate your query, however complex, containing joins, aggregates, withs. I have 2 tables say table1 containing says 3 columns col1, col2 and col3 and table2 which contains col1 and col2.I want to set col3 'some value' where l1 l1 and l2 l2. Here's a TRICK for complex updates: use a trigger on a dummy temporary table which never receives any records. The SELECT statement, to return a temporary table, tmp1, that contains the same rows from the stock table that the subquery returned.
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