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Which query is efficient to check if MySQL Table is empty? COUNT(*) vs. LIMIT?
If you use COUNT(*) around the LEAST() then MySQL scans at least one index, therefore avoid LEAST(COUNT(*)) and use LIMIT.
Let us first create a table. The query to create a table is as follows −
mysql> create table ReturnDemo -> ( -> Id int, -> Name varchar(10) -> ); Query OK, 0 rows affected (0.79 sec)
Now you can insert some records in the table using insert command. The query is as follows −
mysql> insert into ReturnDemo values(100,'Larry'); Query OK, 1 row affected (0.18 sec) mysql> insert into ReturnDemo values(101,'Bob'); Query OK, 1 row affected (0.28 sec) mysql> insert into ReturnDemo values(102,'Sam'); Query OK, 1 row affected (0.17 sec)
Display all records from the table using a select statement. The query is as follows −
mysql> select *from ReturnDemo;
+------+-------+ | Id | Name | +------+-------+ | 100 | Larry | | 101 | Bob | | 102 | Sam | +------+-------+ 3 rows in set (0.00 sec)
The following is the query to check whether a table is empty or not −
mysql> SELECT 1 AS Output FROM ReturnDemo LIMIT 1;
The following is the output displaying 1 i.e. the table isn’t empty −
+--------+ | Output | +--------+ | 1 | +--------+ 1 row in set (0.00 sec)
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