MariaDB [test]> values (3,4),(5,6);

+---+---+

| 3 | 4 |

+---+---+

| 3 | 4 |

| 5 | 6 |

+---+---+

2 rows in set (0.002 sec)

rex=# select * from (values (3,4),(5,6)) as foo(Col1, Col2);

 col1 | col2 

------+------

    3 |    4

    5 |    6

(2 rows)

rex=# select * from (select concat(col1, col2)  from (values (3,4)) as foo(col1,col2)) as foo2 (a);

 a  

----

 34

(1 row)

MariaDB [test]> WITH cte(a,b) as (values (3,4),(5,6) ) select * from cte ;

+---+---+

| a | b |

+---+---+

| 3 | 4 |

| 5 | 6 |

+---+---+

2 rows in set (0.005 sec)

<table primary> ::=

    <table or query name>

    [ <query system time period specification> ]

    [ <correlation or recognition> ]

  | <derived table> <correlation or recognition>

  | <lateral derived table> <correlation or recognition>

  | <collection derived table> <correlation or recognition>

  | <table function derived table> <correlation or recognition>

  | <PTF derived table> [ <correlation or recognition> ]

  | <only spec> [ <correlation or recognition> ]

  | <data change delta table> [ <correlation or recognition> ]

  | <JSON table> <correlation or recognition>

  | <JSON table primitive> <correlation name>

  | <parenthesized joined table>

<correlation or recognition> ::=

  [ AS ] <correlation name>

  [ <parenthesized derived column list> ]

<parenthesized derived column list> ::=

  <left paren> <derived column list> <right paren>

<derived column list> ::=

  <column name list>

<column name list> ::=

  <column name> [ { <comma> <column name> }... ]