Does MySQL or MariaDB support double literals (double precision)?
Though not in the docs explicitly on Numeric Literals. You can make a double precision literal with scientific notation (using e0) which seems to work,

MariaDB [test]&gt; CREATE TABLE foo AS SELECT 1.0e0 AS "se_decimal", 1e0 AS "se_nodecimal", 1.0 AS "decimal";
Query OK, 1 row affected (0.03 sec)
Records: 1  Duplicates: 0  Warnings: 0

MariaDB [test]&gt; SHOW CREATE TABLE foo;
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                     |
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| foo   | CREATE TABLE `foo` (
  `se_decimal` double NOT NULL,
  `se_nodecimal` double NOT NULL,
  `decimal` decimal(2,1) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 |
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)


This is actually supported by the SQL Spec, which shifts the literal from &lt;exact numeric literal&gt; to &lt;approximate numeric literal&gt; when it sees the e or E. From SQL 2011n spec,

&lt;approximate numeric literal&gt; ::=
  &lt;mantissa&gt; E &lt;exponent&gt;


This is what the docs on Numeric Literals presumably refer to when it says,


  Approximate-value numeric literals are represented in scientific notation with a mantissa and exponent. Either or both parts may be signed. Examples: 1.2E3, 1.2E-3, -1.2E3, -1.2E-3.


Though the docs don't say the type, it's double (see above).

See also,


How does the SQL Spec specify literals with a decimal should be handled?