How to use BOOLEAN type in SELECT statement

I have a PL/SQL function with BOOLEAN in parameter:

function get_something(name in varchar2, ignore_notfound in boolean);

This function is a part of 3rd party tool, I cannot change this.

I would like to use this function inside a SELECT statement like this:

 select get_something('NAME', TRUE) from dual;

This does not work, I get this exception:

> ORA-00904: "TRUE": invalid identifier

As I understand it, keyword TRUE is not recognized.

How can I make this work?

You can definitely get Boolean value from a SELECT query, you just can't use a Boolean data-type.

You can represent a Boolean with 1/0.

CASE WHEN (10 > 0) THEN 1  ELSE 0 END (It can be used in SELECT QUERY)

SELECT CASE WHEN (10 > 0) THEN 1  ELSE 0 END AS MY_BOOLEAN_COLUMN
  FROM DUAL

Returns, 1 (in Hibernate/Mybatis/etc 1 is true). Otherwise, you can get printable Boolean values from a SELECT.

SELECT CASE WHEN (10 > 0) THEN 'true' ELSE 'false' END AS MY_BOOLEAN_COLUMN
 FROM DUAL

This returns the string 'true'.

You can build a wrapper function like this:

function get_something(name in varchar2,
                   ignore_notfound in varchar2) return varchar2
is
begin
    return get_something (name, (upper(ignore_notfound) = 'TRUE') );
end;

then call:

select get_something('NAME', 'TRUE') from dual;

It's up to you what the valid values of ignore_notfound are in your version, I have assumed 'TRUE' means TRUE and anything else means FALSE.

From documentation:

> You cannot insert the values TRUE and FALSE into a database column. You cannot select or fetch column values into a BOOLEAN variable. Functions called from a SQL query cannot take any BOOLEAN parameters. Neither can built-in SQL functions such as TO_CHAR; to represent BOOLEAN values in output, you must use IF-THEN or CASE constructs to translate BOOLEANvalues into some other type, such as 0 or 1, 'Y' or 'N', 'true' or 'false', and so on.

You will need to make a wrapper function that takes an SQL datatype and use it instead.

> The BOOLEAN data type is a PL/SQL data > type. Oracle does not provide an > equivalent SQL data type (...) you can > create a wrapper function which maps a > SQL type to the BOOLEAN type.

Check this: http://forums.datadirect.com/ddforums/thread.jspa?threadID=1771&tstart=0&messageID=5284

select get_something('NAME', sys.diutil.int_to_bool(1)) from dual;

Compile this in your database and start using boolean statements in your querys.

note: the function get's a varchar2 param, so be sure to wrap any "strings" in your statement. It will return 1 for true and 0 for false;

select bool('''abc''<''bfg''') from dual;

CREATE OR REPLACE function bool(p_str in varchar2) return varchar2 
 is
 begin
  
 execute immediate ' begin if '||P_str||' then
          :v_res :=  1;
       else
          :v_res :=  0;
       end if; end;' using out v_res;
       
       return v_res;
       
 exception 
  when others then 
    return '"'||p_str||'" is not a boolean expr.';
 end;
/

With Oracle 12, you can use the WITH clause to declare your auxiliary functions. I'm assuming your get_something function returns varchar2:

with
  function get_something_(name varchar2, ignore_notfound number)
  return varchar2 
  is
  begin
    -- Actual function call here
    return get_something(name, not ignore_notfound = 0);
  end get_something_;

  -- Call auxiliary function instead of actual function
select get_something_('NAME', 1) from dual;

Of course, you could have also stored your auxiliary function somewhere in the schema as shown in this answer, but by using WITH, you don't have any external dependencies just to run this query. I've blogged about this technique more in detail here.

The answer to this question simply put is: Don't use BOOLEAN with Oracle-- PL/SQL is dumb and it doesn't work. Use another data type to run your process.

A note to SSRS report developers with Oracle datasource: You can use BOOLEAN parameters, but be careful how you implement. Oracle PL/SQL does not play nicely with BOOLEAN, but you can use the BOOLEAN value in the Tablix Filter if the data resides in your dataset. This really tripped me up, because I have used BOOLEAN parameter with Oracle data source. But in that instance I was filtering against Tablix data, not SQL query.

If the data is NOT in your SSRS Dataset Fields, you can rewrite the SQL something like this using an INTEGER parameter:

__

<ReportParameter Name="paramPickupOrders">
  <DataType>Integer</DataType>
  <DefaultValue>
	<Values>
	  <Value>0</Value>
	</Values>
  </DefaultValue>
  <Prompt>Pickup orders?</Prompt>
  <ValidValues>
	<ParameterValues>
	  <ParameterValue>
		<Value>0</Value>
		<Label>NO</Label>
	  </ParameterValue>
	  <ParameterValue>
		<Value>1</Value>
		<Label>YES</Label>
	  </ParameterValue>
	</ParameterValues>
  </ValidValues>
</ReportParameter>

...

<Query>
<DataSourceName>Gmenu</DataSourceName>
<QueryParameters>
  <QueryParameter Name=":paramPickupOrders">
	<Value>=Parameters!paramPickupOrders.Value</Value>
  </QueryParameter>
<CommandText>
    where 
		(:paramPickupOrders = 0 AND ordh.PICKUP_FLAG = 'N'
		OR :paramPickupOrders = 1 AND ordh.PICKUP_FLAG = 'Y' )

If the data is in your SSRS Dataset Fields, you can use a tablix filter with a BOOLEAN parameter:

__

</ReportParameter>
<ReportParameter Name="paramFilterOrdersWithNoLoad">
  <DataType>Boolean</DataType>
  <DefaultValue>
	<Values>
	  <Value>false</Value>
	</Values>
  </DefaultValue>
  <Prompt>Only orders with no load?</Prompt>
</ReportParameter>

...

<Tablix Name="tablix_dsMyData">
<Filters>
  <Filter>
	<FilterExpression>
		=(Parameters!paramFilterOrdersWithNoLoad.Value=false) 
		or (Parameters!paramFilterOrdersWithNoLoad.Value=true and Fields!LOADNUMBER.Value=0)
	</FilterExpression>
	<Operator>Equal</Operator>
	<FilterValues>
	  <FilterValue DataType="Boolean">=true</FilterValue>
	</FilterValues>
  </Filter>
</Filters>

How about using an expression which evaluates to TRUE (or FALSE)?

select get_something('NAME', 1 = 1) from dual

PL/SQL is complaining that TRUE is not a valid identifier, or variable. Set up a local variable, set it to TRUE, and pass it into the get_something function.