Oracle Select Syntax into Postgres
I am converting Oracle Syntax into Postgres
SELECT MSN_INT_ID,
M开发者_如何学CO_INT_ID,
'Y' "AIRMOVE"
FROM MISSION_OBJECTIVE
WHERE MO_MSN_CLASS_CD = 'AMV'
GROUP BY MSN_INT_ID,
MO_INT_ID
This part is confusing me:
SELECT MSN_INT_ID,
MO_INT_ID,
'Y' "AIRMOVE"
What is the 'Y' "AIRMOVE" doing?
The snippet 'Y' "AIRMOVE"
introduces a computed column into the select-list named AIRMOVE
whose value is always 'Y'
.
It's a computed column, using a statically defined value.
Part of the confusion may be coming from PostgreSQL 8.3 or earlier, where the "AS" keyword is not optional.
Change:
'Y' "AIRMOVE"
To:
'Y' AS "AIRMOVE"
And it should work fine. The keyword is optional starting in version 8.4, although I advocate always including it to avoid issues exactly like this one.
精彩评论