Hi Bo,

May this link helps:

https://success.outsystems.com/Documentation/10/Developing_an_Application/Use_Data/Query_Data/Write_Your_Own_SQL_Queries

regards,

IB

hi Bo,

here it is the statement:

and for example:

Suppose the SQL:

You need to define the Output "mystring" above in the Data tab - the structure attribute (in my case str) must match to your result query, either the number and the data types:

regards,

IB

Hi Bo Tao Dong,

If you don't know how to write SQL then you probably should stay away from the SQL tool until you learn it and rely on Aggregates for your queries.

If you do know your way around the SQL language, then you just need to write your SQL query on the SQL tab there, and keep in mind that you should use the {SomeEntity} syntax to represent the table that holds the records of SomeEntity, {SomeEntity}.[SomeAttribute] to represent the column that holds the value of SomeEntity.SomeAttribute, and {SomeEntity}.* to represent all relevant columns that hold values of SomeEntity. Everything else is going to be passed on to the database engine as is, so either write standard SQL or use the correct SQL dialect for your database.

If you don't know how to write SQL then you probably should stay away from the SQL tool until you learn it and rely on Aggregates for your queries.

Jorge Martins wrote:

This. And also, and perhaps more importantly, even if you know SQL, or perhaps especially if you know SQL, stay away from the SQL statement unless it's really necessary to use it. Almost anything mundane can be done with Aggregates, and they have many advantages over SQL.

Your words give me another way to solve the problem,thanks for that.

The idea is correct, you have some syntax issues, but most of all, you'll have to give a name to the result of your inner query, not the attribute itself... something like this should work:

SELECT
  {A}.*,
  B_Count.*
FROM
  (SELECT COUNT({B}.[X]) FROM {B}) AS B_Count,
  {A}

Edited: and you can have more than one output structure/Entity... you could simply configure your SQL tool to return as output structure: an entity of type A and, a structure with a single (Long?) Integer attribute.