PostgreSQL/Math Functions/sqrt

sqrt(x): Returns the square root of x

postgres=#
postgres=# -- sqrt(x): Returns the square root of x
postgres=# SELECT sqrt(2.0), sqrt(4.0),
postgres-#        sqrt(pow(2.0, 2)) AS inverse_example;
       sqrt        |       sqrt        |  inverse_example
-------------------+-------------------+--------------------
 1.414213562373095 | 2.000000000000000 | 2.0000000000000000
(1 row)
postgres=#