Make syntax of "SELECT ... INTO" sql standard compliant [CORE1382]

[firebird-automations]

Submitted by: lacak (lacak)

SQL Stand. 92/2003 defines :

SELECT [ <set quantifier> ] <select list> INTO <select target list>

INTO clause before FROM clause

(Today Firebird allows INTO only as last clause of SELECT : singleton_select : select INTO variable_list )

[firebird-automations]

Modified by: @pcisar

Workflow: jira [ 12690 ] => Firebird [ 14173 ]

[dyemanov]

Since we'll have to support both positions (for backward compatibility), I doubt this feature gonna add something but confusion.