在 Snowflake 中连接表时添加计算列
Adding a calculated column while joining tables in Snowflake
我有 4 个表 A、B、C 和 D，每个表有 3 列
A- aa, ab, ac
B- ba, bb, bc
C- ca, cb, cc
D- da, db, dc
我需要连接 4 个表并添加一个新的计算列 (aa + ab + ac)。我的查询是
SELECT A.aa, A.ab, A.ac, B.ba, B.bb, B.bc, C.ca, C.cb, C.cc, D.da, D.db, D.dc,(A.aa + A.ab + A.ac) AS total
FROM A
LEFT JOIN B
ON A.aa = B.ba
LEFT JOIN C
ON A.ab = C.ca
LEFT JOIN D
ON A.aa = D.da;
表连接良好，但所有行的计算列 returns NULL。我哪里出错了，还有其他方法吗？
为了完整起见，将@Fred 的答案从评论移至答案：
Seems like some of aa, ab, ac are NULLs so sum is therefore NULL. Apply ZEROIFNULL() function to each column before summing, to treat missing values as zero?
https://docs.snowflake.com/en/sql-reference/functions/zeroifnull.html
我有 4 个表 A、B、C 和 D，每个表有 3 列
A- aa, ab, ac
B- ba, bb, bc
C- ca, cb, cc
D- da, db, dc
我需要连接 4 个表并添加一个新的计算列 (aa + ab + ac)。我的查询是
SELECT A.aa, A.ab, A.ac, B.ba, B.bb, B.bc, C.ca, C.cb, C.cc, D.da, D.db, D.dc,(A.aa + A.ab + A.ac) AS total
FROM A
LEFT JOIN B
ON A.aa = B.ba
LEFT JOIN C
ON A.ab = C.ca
LEFT JOIN D
ON A.aa = D.da;
表连接良好，但所有行的计算列 returns NULL。我哪里出错了，还有其他方法吗？
为了完整起见，将@Fred 的答案从评论移至答案：
Seems like some of aa, ab, ac are NULLs so sum is therefore NULL. Apply
ZEROIFNULL()function to each column before summing, to treat missing values as zero?
https://docs.snowflake.com/en/sql-reference/functions/zeroifnull.html