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Any way to select without causing locking in MySQL?
...s/22-mysql-with-nolock.aspx
in MS SQL Server you would do the following:
SELECT * FROM TABLE_NAME WITH (nolock)
and the MYSQL equivalent is
SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED ;
SELECT * FROM TABLE_NAME ;
SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ ;
EDIT
Mic...
SQL “select where not in subquery” returns no results
...MySQL
There are three ways to do such a query:
LEFT JOIN / IS NULL:
SELECT *
FROM common
LEFT JOIN
table1 t1
ON t1.common_id = common.common_id
WHERE t1.common_id IS NULL
NOT EXISTS:
SELECT *
FROM common
WHERE NOT EXISTS
(
SELECT NULL
FROM ...
Can you have if-then-else logic in SQL? [duplicate]
I need to do select data from a table based on some kind of priority like so:
7 Answers
...
How to select from subquery using Laravel Query Builder?
... Note that if you have a complex query as a belongsToMany as subselect you have to add getQuery() twice => $sub->getQuery()->getQuery()
– Jordi Puigdellívol
Aug 28 '15 at 14:23
...
What is the simplest SQL Query to find the second largest value?
...
SELECT MAX( col )
FROM table
WHERE col < ( SELECT MAX( col )
FROM table )
share
|
improve this answ...
When to use Common Table Expression (CTE)
...ing well? Can someone give me a simple example of limitations with regular select, derived or temp table queries to make the case of CTE? Any simple examples would be highly appreciated.
...
How do I use variables in Oracle SQL Developer?
... other stuff didn't work for me, but this did:
define value1 = 'sysdate'
SELECT &&value1 from dual;
Also it's the slickest way presented here, yet.
(If you omit the "define"-part you'll be prompted for that value)
...
How do I use ROW_NUMBER()?
...
For the first question, why not just use?
SELECT COUNT(*) FROM myTable
to get the count.
And for the second question, the primary key of the row is what should be used to identify a particular row. Don't try and use the row number for that.
If you returned Ro...
How do SQL EXISTS statements work?
... criteria -- this is why it can be faster than IN. Also be aware that the SELECT clause in an EXISTS is ignored - IE:
SELECT s.*
FROM SUPPLIERS s
WHERE EXISTS (SELECT 1/0
FROM ORDERS o
WHERE o.supplier_id = s.supplier_id)
...should hit a division by zero error...
Which is fastest? SELECT SQL_CALC_FOUND_ROWS FROM `table`, or SELECT COUNT(*)
...irm this - I just updated a query with 4 joins on a 168,000 row database. Selecting just the first 100 rows with a SQL_CALC_FOUND_ROWS took over 20 seconds; using a separate COUNT(*) query took under 5 seconds (for both count + results queries).
– Sam Dufel
Ju...