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I have a table with given structure, now I want to write a query that will transfer 2 xx product from status 1 to say status 2. the child code is irrelevant presently to me.
master_code| child_code | status_code -----------|------------|------------ xx | xx1 | 1 xx | xx2 | 1 xx | xx3 | 1 xx | xx4 | 2 xx | xx5 | 2 yy | yy1 | 3 yy | yy2 | 2 zz | zz1 | 1 zz | zz2 | 1 I have implemented basic checks, and when I used
update only product_child set product_status=1 where product_status=2 all three xx's got code 2, I want control over that, I was expecting only one xx will get code change with this command
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The LIMIT clause can be used with the OFFSET clause to skip a specific number of rows before returning the query for the LIMIT clause. Syntax:SELECT * FROM table LIMIT n OFFSET m; Let's analyze the syntax above. The LIMIT clause returns a subset of “n” rows from the query result.
PostgreSQL does not impose a limit on the number of rows in any table. There is no PostgreSQL-imposed limit on the number of indexes you can create on a table. Of course, performance may degrade if you choose to create more and more indexes on a table with more and more columns.
When using Postgres if you do need writes exceeding 10,000s of INSERT s per second we turn to the Postgres COPY utility for bulk loading. COPY is capable of handling 100,000s of writes per second.
If a limit count is given, no more than that many rows will be returned (but possibly fewer, if the query itself yields fewer rows). LIMIT ALL is the same as omitting the LIMIT clause, as is LIMIT with a NULL argument. OFFSET says to skip that many rows before beginning to return rows.
If you do not care which row gets updated, something I would be very wary of doing (please add a PK to the table for this really), then you could use something like the following:
UPDATE product_child SET product_status = 1 WHERE CTID IN ( SELECT CTID FROM product_child WHERE product_status = 2 and master_code = 'xx' LIMIT 1 ) CTID is a unique row identifier - and by limiting the subselect to 1 record we get back one CTID corresponding to a row that meets the WHERE clause.
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i found a way
update only product_child set product_status =1 where product_child_code in (select product_child_code from product_child where product_code = get_product_code('Baby Crib') and product_status = 2 limit 5) If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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