


*Merge Count() results from multiple tables into a single row**
To get the count of single row results from multiple tables, for example:
<code>Count_1 Count_2 123 456</code>
Where tab1 and tab2 are source tables, please use the query in the following format:
SELECT ( SELECT COUNT(*) FROM tab1 ) AS count1, ( SELECT COUNT(*) FROM tab2 ) AS count2 FROM dual;
Instructions:
- The outer
SELECT
statement acts as a placeholder for returning multiple count results to a single row. - The inner
SELECT
statement calculates the count for each table. -
dual
is a built-in table that contains a single row and is used here as a virtual table. Including it ensures that the outerSELECT
statement always returns a single row, even if the source table is empty. - Each count result is assigned an alias (count1 and count2) to identify them in the final result.
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