Converting a subquery into a JOIN can be pretty straightforward: IN clause FROM TABLE_X x WHERE x.col IN (SELECT y.col FROM TABLE_Y y) …can be converted to: FROM TABLE_X x JOIN TABLE_Y y ON y.col = x.col Your JOIN criteria is where you have direct comparison. EXISTS clause But there are complications when you look … Read more
Straight answer: you can’t. The Access Database Engine simple does not support the vanilla SQL-92 scalar subquery syntax even when in its own so-called ANSI-92 Query Mode. You are forced to use its own proprietary syntax which does not enforce the scalar requirement i.e. is unsafe and will pick a value arbitrarily and silently**. Further, … Read more
How about: $query = “SELECT p1.id, (SELECT COUNT(1) FROM post_table p2 WHERE p2.parent_id = p1.id) as num_children FROM post_table p1 WHERE p1.parent_id = 0”; or if you put an alias on the p1.id, you might say: $query = “SELECT p1.id as p1_id, (SELECT COUNT(1) FROM post_table p2 WHERE p2.parent_id = p1.id) as num_children FROM post_table … Read more
In Oracle we don’t include the AS when declaring a table alias. Instead of ) AS TABLE_RESOLVERS write ) TABLE_RESOLVERS This is one example when Oracle syntax is more restrictive than some other flavours of SQL. It is also inconsistent with the declaration of column aliases, which is unfortunate but almost certainly it’s too complex … Read more
There is an excellent summary of the available string aggregation techniques on Tim Hall’s site.
Technically, to remove the error, add LIMIT 1 to the subquery to return at most 1 row. The statement would still be nonsense. … ‘SELECT store_key FROM store LIMIT 1’ … Practically, you want to match rows somehow instead of picking an arbitrary row from the remote table store to update every row of your … Read more
That method doesn’t work in SQL Server. You can accomplish the same thing in a couple different ways: 1.) Use the code for each aliased column instead of the alias: (SELECT COUNT(*) FROM UserEvent UE WHERE UE.EventTypeID = 1 AND UE.PracticeID = au.PracticeID AND (UE.EventDate BETWEEN @Date1 and @Date2) – COUNT(CASE WHEN udi.DevicePlatform = ‘iOS’ … Read more
You need to alias the subquery. SELECT name FROM (SELECT name FROM agentinformation) a or to be more explicit SELECT a.name FROM (SELECT name FROM agentinformation) a
What is a LATERAL join? The feature was introduced with PostgreSQL 9.3. The manual: Subqueries appearing in FROM can be preceded by the key word LATERAL. This allows them to reference columns provided by preceding FROM items. (Without LATERAL, each subquery is evaluated independently and so cannot cross-reference any other FROM item.) Table functions appearing … Read more
select @code:= SUM(field1 + field2), @code+1 from abc; But, please be aware of the following (from the MySQL 5.6 docs): As a general rule, other than in SET statements, you should never assign a value to a user variable and read the value within the same statement. For example, to increment a variable, this is … Read more