Is the character “A” a reserved keyword in Oracle Database? [on hold]
Is the character “A” a reserved keyword in Oracle Database? [on hold] scenario: In Oracle Database, This SQL it's much slower: SELECT * FROM TBL_MAIN A, TBL_CHILD_1 B, TBL_CHILD_2 C, TBL_CHILD_3 D, TBL_CHILD_4 E WHERE A.ID_MAIN = B.ID_MAIN AND A.ID_MAIN = C.ID_MAIN AND A.ID_MAIN = D.ID_MAIN AND A.ID_MAIN = E.ID_MAIN; than that: SELECT * FROM TBL_MAIN X, TBL_CHILD_1 B, TBL_CHILD_2 C, TBL_CHILD_3 D, TBL_CHILD_4 E WHERE X.ID_MAIN = B.ID_MAIN AND X.ID_MAIN = C.ID_MAIN AND X.ID_MAIN = D.ID_MAIN AND X.ID_MAIN = E.ID_MAIN; In other words, When I have 3 or more tables joined if I use "A" as an aliasing for "TBL_MAIN" table, it results in a slower query. It becomes worst when I added more tables in an inner join with table "TBL_MAIN" AS "A". What is happening? This question appears to be off-topic. The users who voted to close gave this specific reason: I don't believe you. What does the explain plan show for these two?...