What does a SQL query return if nothing is found?

If the inner query has a matching row, then 1 is returned. The outer query (with ISNULL) then returns this value of 1. If the inner query has no matching row, then it doesn’t return anything. The outer query treats this like a NULL, and so the ISNULL ends up returning 0.

How do I assign a default value if no rows returned from the SELECT query mysql?

SELECT COALESCE(col1, ‘defaultValue’) col1, COUNT(*) cRows FROM table1 WHERE colx = ‘filter’; This query returns 2 columns: The first is the value of the column searched with the default value set in case the row does not exist. The second column returns the number of rows with the filter in the table.

How do I SELECT default value in SQL?

Use SSMS to specify a default

1. In Object Explorer, right-click the table with columns for which you want to change the scale and select Design.
2. Select the column for which you want to specify a default value.
3. In the Column Properties tab, enter the new default value in the Default Value or Binding property.

How do I get first or default in SQL?

The FirstOrDefault() method returns a first specific element of a sequence or default value if that element is not found in the sequence. Whenever FirstOrDefault is used, the query can return any amount of results but you state that you only want the first one.

Does select return NULL values?

The IS NULL condition is used in SQL to test for a NULL value. It returns TRUE if a NULL value is found, otherwise it returns FALSE. It can be used in a SELECT, INSERT, UPDATE, or DELETE statement.

What is Isnull function SQL Server?

SQL Server ISNULL() Function The ISNULL() function returns a specified value if the expression is NULL. If the expression is NOT NULL, this function returns the expression.

What does FirstOrDefault return if not found?

FirstOrDefault returns the default value of a type if no item matches the predicate. For reference types that is null . Thats the reason for the exception.

How to return default values for each column in SQL Server?

This solution allows you to return default values for each column also, for example: SELECT CASE WHEN S.Id IS NULL THEN 0 ELSE S.Col1 END AS Col1, S.Col2, ISNULL (S.Col3, 0) AS Col3 FROM (SELECT @Id AS Id) R LEFT JOIN Sites S ON S.Id = R.Id AND S.Status = 1 AND Show activity on this post.

How to return a value if no row found in MySQL?

In MySQL you can use IFNULL to return a specified value if no row found i.e. when it returns NULL ex- SELECT IFNULL ((SELECT col1 FROM table1 WHERE col1 in (your_list)),’default_value_you_want_to_return’); you can see examples of IFNULL here – IFNULL Example

Why does my SQL query return 0 when there is null?

If the inner query has no matching row, then it doesn’t return anything. The outer query treats this like a NULL, and so the ISNULL ends up returning 0.

How to use sub-queries to get null values?

By using a sub query, the top level query gets a field with a null value, and both ISNULL and COALESCE will work as you want/expect them to. Show activity on this post. SELECT CASE WHEN S.Id IS NOT NULL AND S.Status = 1 AND …)