SQL 将总和转换为浮点数的强制转换语法
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Cast syntax to convert a sum to float
提问by MAK
Using PostgreSQL 9.3, I want to convert the calculated values to data type float.
使用 PostgreSQL 9.3，我想将计算值转换为数据类型float。
My first attempt:
我的第一次尝试：
SELECT float(SUM(Seconds))/-1323 AS Averag;
Gives me this error:
给我这个错误：
syntax error at or near "SUM"
syntax error at or near "SUM"
My second attempt:
我的第二次尝试：
SELECT to_float(SUM(Seconds))/-1323 AS Averag;
Gives me this error:
给我这个错误：
function to_float(bigint) does not exist
function to_float(bigint) does not exist
回答by Erwin Brandstetter
There is also the shorthand cast syntax:
还有速记强制转换语法：
SELECT sum(seconds)::float / -1323 AS averag;回答by Mureinik
You need to use the castsyntax:
您需要使用以下cast语法：
SELECT CAST (SUM(Seconds) AS FLOAT)/-1323 AS Averag;
回答by Souvik
It is not exact casting but a trick to do the job :) and works almost in any language.
这不是精确的铸造，而是完成工作的技巧:) 并且几乎可以在任何语言中使用。
SELECT SUM(Seconds)/-1323.0 AS Averag;
SELECT SUM(Seconds)/-1323.0 AS Averag;
OR
或者
SELECT SUM(Seconds)*1.0/-1323 AS Averag;
SELECT SUM(Seconds)*1.0/-1323 AS Averag;
