select count(*) from (select * from tab)

Hello

If I execute

  select count(*) from (select * from tab)

I get the error 'General error;-2010 POS(1) Assignment impossible, char
value too long' if
tab is a table that contains a column of type long (that seems to be the
criteria).

[The above statement can always be made simpler (select count(*) from
tab) but sometimes (if for example the main query 'select * from tab' is
available) it is convenient to simply add 'select count(*) from(' +
origquery + ')'.]



Is that behaviour a bug or a feature?


The doc:
----------
-2010: Assignment impossible, char value too long 

Explanation:

In an <INSERT statement> with a <QUERY EXPRESSION> or in an <UPDATE
statement>, the attempt was made to assign a character string to a
column of data type CHAR. This character string was too long. The error
message is returned for the first occurring value of excess length, not
while analyzing the maximum column lengths.

User Action:

Use SELECT ... WHERE LENGTH (<column name>) > <unsigned integer> to find
out the rows which are too long. The length of the corresponding column
can be increased by an <ALTER TABLE statement>
----------


Thanks,
Gabriel

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