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What is the meaning of sqlType in registerOutParameter jdbc?

I am using jdbc CallableStatement to execute procedures in a MySQL database. While writing unit tests, I came across unusual behavior regarding the registerOutParameter method.

Used SQL Procedures

PROCEDURE TEST_DOUBLE( OUT val DOUBLE ) BEGIN SET val = 2.5; END
PROCEDURE TEST_TEXT( OUT val TEXT ) BEGIN SET val = 'test'; END

Test

statement = connection.prepareCall( "CALL TEST_DOUBLE(?)" );
statement.registerOutParameter( "val" , java.sql.Types.INTEGER );
statement.execute();
statement.getInt( "val" ); //Integer 2
statement.getDouble( "val" ); //Double 2.5
statement.getString( "val" ); //String "2.5"

statement = connection.prepareCall( "CALL TEST_TEXT(?)" );
statement.registerOutParameter( "val" , java.sql.Types.INTEGER );
statement.execute();
statement.getInt( "val" ); //Invalid value for getInt
statement.getDouble( "val" ); //Invalid value for getDouble
statement.getString( "val" ); //String "test"

statement = connection.prepareCall( "CALL TEST_TEXT(?)" );
statement.registerOutParameter( "val" , 0 );
statement.execute();
statement.getInt( "val" ); //Invalid value for getInt
statement.getDouble( "val" ); //Invalid value for getDouble
statement.getString( "val" ); //String "test"

etc.

My point is the values ​​of java.sql.Types. *, passed to registerOutParameter do not seem to do anything ... No matter what type of sql I pass, it all depends on calling the correct getter method and the actual value returned by the database.

Can I just go through 0 everywhere and still work fine? Why is this parameter passed then? Or maybe this database is related, but does it make sense for other databases?

+4
2

, . Oracle, , :

statement = connection.prepareCall("CALL_TEST_NUMBER(?)");
statement.registerOutParameter("val", java.sql.Types.INTEGER);
statement.execute();
statement.getInt("val");       // 2
statement.getDouble("val");    // 2.5
statement.getString("val");    // "2.5"

statement = connection.prepareCall("CALL TEST_TEXT(?)");
statement.registerOutParameter("val", java.sql.Types.INTEGER);
statement.execute();   //  java.sql.SQLSyntaxErrorException: ORA-01722: invalid number
0

, jdbc . , (java.sql.Types.INTEGER), int (public static final int INTEGER), java.sql.Types, , 0 (, 0 java.sql.Types.INTEGER ). , .

java.sql.Type(, java.sql.Type.ARRAY), , , classCast , jdbc , , (a ) , ().

0

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