I am trying to do something like this:
select char_length(select text_field from table where key = 1)
This won't work, and I presume, because the return type of a query is a table, not a string or text variable.
Is there a way to specify row,col of the result from a select statement?
edit: I overlooked to mention, that char_length is a function.
When passing the result of a query to a function, simply wrap the query in brackets:
select char_length((select text_field from table where key = 1));
The outer set of brackets is for the function, the inner set converts a query to a result.
This syntax is not specific to postgres - it applies to all SQL servers.
This link shows the above code executing correctly (thanks to @Fahim Parkar for this)
Although, you could re-factor your query to not require this syntax, nevertheless this is how you "pass the result of a query to a function".
select char_length(text_field) from "table" where key = 1
Assuming key is a primary key or unique key the first example below will work. It works only if the sub-query returns only 1 row. The second example will work for 1 or more rows.
select char_length((select text_field from table where key = 1));
select char_length(text_field) from table where key = 1;
It should be
select char_length(text_field) from "table" where key = 1
Also I believe, your table name is not table.
text_fieldto the function? Is there a reason why you do it that way?