How do you write a case statement in join condition in SQL Server?

Can you use CASE statement in join condition?

A conditional column join is a fancy way to let us join to a single column and to two (or more) columns in a single query. We can accomplish this by using a case statement in the on clause of our join. A case statement allows us to test multiple conditions (like an if/else if/else) to produce a single value.

How use in condition in SQL case?

The case statement in SQL returns a value on a specified condition. We can use a Case statement in select queries along with Where, Order By, and Group By clause. It can be used in the Insert statement as well.

Insert statement with CASE statement.

Value Description Required value in Employee table
1 Female Employee F

How do you use CTE in a case statement?

This goes for both column 4 and column 5. So change your query to something like this: WITH CTE AS ( SELECT ID, NAME, DEPT, CASE WHEN Fixed = 1 THEN ‘Yes’ ELSE ” END AS [Expr1], CASE WHEN NotFixed = 1 THEN ‘Yes’ ELSE ” END AS [Expr2], . . . )

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How do you give a join a condition?

To use the WHERE clause to perform the same join as you perform using the INNER JOIN syntax, enter both the join condition and the additional selection condition in the WHERE clause. The tables to be joined are listed in the FROM clause, separated by commas. This query returns the same output as the previous example.

What is equi join?

An equi-join is a basic join with a WHERE clause that contains a condition specifying that the value in one column in the first table must be equal to the value of a corresponding column in the second table.

Can we use and in case statement in SQL?

CASE must include the following components: WHEN , THEN , and END . ELSE is an optional component. You can make any conditional statement using any conditional operator (like WHERE ) between WHEN and THEN . This includes stringing together multiple conditional statements using AND and OR .

How do you write a multiple case statement in SQL SELECT query?

You can get a nearly identical runtime and query plan by writing the query like this: SELECT (case A. column1 when ‘1’ then (select value from B where B. clientId=100 and ‘1’=B.Id) when ‘2’ then (select value from C where C.

Can I use case in where clause SQL Server?

CASE STATEMENT IN WHERE CLAUSE:

We can use a case statement in Where, Order by and Group by clause. … So, by using a CASE statement with the where condition displays the result.

How do you optimize a query?

It’s vital you optimize your queries for minimum impact on database performance.

  1. Define business requirements first. …
  2. SELECT fields instead of using SELECT * …
  3. Avoid SELECT DISTINCT. …
  4. Create joins with INNER JOIN (not WHERE) …
  5. Use WHERE instead of HAVING to define filters. …
  6. Use wildcards at the end of a phrase only.
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Can I use CTE in stored procedure?

According to the CTE documentation, Common Table Expression is a temporary result set or a table in which we can do CREATE, UPDATE, DELETE but only within that scope. That is, if we create the CTE in a Stored Procedure, we can’t use it in another Stored Procedure.

Why CTE is used in SQL Server?

Why to use a CTE

In SQL, we will use sub-queries to join the records or filter the records from a sub-query. Whenever we refer the same data or join the same set of records using a sub-query, the code maintainability will be difficult. A CTE makes improved readability and maintenance easier.

Which are the join types in join condition?

Join types: inner join, left outer join, right outer join, full outer join. The keyword inner and outer are optional since the rest of the join type enables us to deduce whether the join is an inner join or an outer join. SQL-92 also provides two other join types: cross join: an inner join without a join condition.

Can we use where with join in SQL?

Yes. ON should be used to define the join condition and WHERE should be used to filter the data. … To go more in depth we will cover the two use cases that either WHERE or ON can support: Joining data.