In this answer, there is a trick which allows to use the ROW_NUMBER() windowed function with a ‘constant’ in the ORDER BY clause:
SELECT ROW_NUMBER() OVER (ORDER BY $/0) FROM master..spt_values
After some search in Google, I can’t find what dollar sign means in this context?
I’ve tried to execute a simple query:
SELECT $;
And it returns 0.
Could somebody explain this?
Advertisement
Answer
It’s just a money constant (what T-SQL calls literals).
You presumably would have been less surprised if you saw the expression $2.50, which would just be another constant.
Some other examples: select £,¢,¤,¥,€ all return 0s also.
It can be tricky to determine what type of data you’re looking at in T-SQL. One trick, if you suspect you know what type it is is to pick an incompatible type and attempt the conversion:
select CONVERT(date,$)
Result:
Msg 529, Level 16, State 2, Line 1 Explicit conversion from data type money to date is not allowed.