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When to use having condition in a subquery?
HAVING condition: It is used to filter groups based on the specified condition. In the third case, the filtering of groups is done based on the result of the subquery.
How are subqueries used in the where clause?
A subquery in the WHERE clause helps in filtering the rows for the result set, by comparing a column in the main table with the results of the subquery. Here is an example to understand subqueries in the WHERE clause.
When to use a subquery in a SQL statement?
In your example using CASE, you are not using a CASE “statement” — you are using a CASE expression, which happens to be embedded within a SQL statement. You can use a subquery in that case because it’s within the context of a SQL statement, not a procedural statement.
Can you use if else in a SELECT query?
If/else constructions are not supposed to work into a Select query. For this particular query, could you not acheive the desired result using a single SELECT with the February condition in your WHERE clause?
When to use a subquery in an expression?
You can write a subquery in an expression or in a Structured Query Language (SQL) statement in SQL view. You can use a subquery as a field alias. Use a subquery as a field alias when you want to use the subquery results as a field in your main query.
Why are the results of both subqueries the same?
Strangely, both queries returned the same result. When looking at the explain plan of query 1, it looked like when the subquery was executed, because the condition A2 is something was not applicable to the subquery, it was deferred for use as a filter on the main query results.
How to add subqueries to a table in SQL?
Once the inner query runs, the outer query will run using the results from the inner query as its underlying table: SELECT sub.* FROM ( < > ) sub WHERE sub.resolution = ‘NONE’ Subqueries are required to have names, which are added after parentheses the same way you would add an alias to a normal table.
Which is the result of a subquery in SQL?
In the first case, the result of the subquery will act as the source. In the second case, data will be fetched from table_name_1. WHERE condition: It is used to specify the conditions to filter records. In the second case, the rows will be filtered according to the comparison between the results of the subquery and the mentioned column.
When this SQL executes the following comparisons are made: The WHERE clause returns all records where the EXISTS clause is TRUE. The EXIST clause uses a correlated sub query. The outer query is correlated to the inner query by SalesPersonID.