sql - Show column value of one of left joins -

in query shows 1 row if sal.id_amenaza exists in mft or mfa schemas, want show mft.id_amenaza or mfa.id_amenaza (if exist in table) in resulting row.

in actual query dont require id_amenaza. how can show?

select sal.id_salvaguarda, sal.descripcion, sal.eficacia agr_salvaguardas sal       left join agr_mit_frec_tipo mft      on sal.id_salvaguarda = mft.id_salvaguarda , mft.id_amenaza = 5043       left join agr_mit_frec_act mfa      on sal.id_salvaguarda = mfa.id_salvaguarda , mfa.id_amenaza = 5043    mft.id_salvaguarda not null or       mfa.id_salvaguarda not null group sal.id_salvaguarda, sal.descripcion, sal.eficacia 

i need obtain table this:

id_salvaguarda | descripcion | eficacia | id_amenaza 5061           | pre-01      | 100      | 5043 

thank in advance.

this should work you:

select sal.id_salvaguarda, sal.descripcion, sal.eficacia, 5043 id_amenaza agr_salvaguardas sal       left join agr_mit_frec_tipo mft      on sal.id_salvaguarda = mft.id_salvaguarda , mft.id_amenaza = 5043       left join agr_mit_frec_act mfa      on sal.id_salvaguarda = mfa.id_salvaguarda , mfa.id_amenaza = 5043    mft.id_salvaguarda not null or       mfa.id_salvaguarda not null group sal.id_salvaguarda, sal.descripcion, sal.eficacia; 

because query guarantees there @ least 1 match.

however, more general solution is:

select sal.id_salvaguarda, sal.descripcion, sal.eficacia,        coalesce(mft.id_amenaza, mfa.id_amenaza) id_amenaza . . . 

the function coalesce() returns first value not null in list of arguments.