• Igor Babaev's avatar
    MDEV-17154 Multiple selects from parametrized CTE fails with syntax error · 3473e045
    Igor Babaev authored
    This patch fills a serious flaw in the implementation of common table
    expressions. Before this patch an attempt to prepare a statement from
    a query with a parameter marker in a CTE that was used more than once
    in the query ended up with a bogus error message. Similarly if a statement
    in a stored procedure contained a CTE whose specification used a
    local variables and this CTE was referred to more than once in the
    statement then the server failed to execute the stored procedure returning
    a bogus error message on a non-existing field.
    
    The problems appeared due to incorrect handling of parameter markers /
    local variables in CTEs that were referred more than once.
    
    This patch fixes the problems by differentiating between the original
    occurrences of a parameter marker / local variable used in the
    specification of a CTE and the corresponding occurrences used
    in copies of this specification. These copies are substituted
    instead of non-first references to the CTE.
    
    The idea of the fix and even some code were taken from the MySQL
    implementation of the common table expressions.
    3473e045
sql_lex.h 100 KB