SELECT T.cnomteleph,; CAST(NVL( SUBSTR( TTOC( A1.debut ) , 12 , 5 ), "" ) AS c(5 ) )AS D01 ,; CAST(SUBSTR( TTOC( A2.debut ) , 12 , 5 ) AS c(5 ) )AS D02 ,; CAST(SUBSTR( TTOC( A3.debut ) , 12 , 5 ) AS c(5 ) )AS D03 ,; CAST(SUBSTR( TTOC( A4.debut ) , 12 , 5 ) AS c(5 ) )AS D04 ,; CAST(SUBSTR( TTOC( A5.debut ) , 12 , 5 ) AS c(5 ) )AS D05 ,; CAST(SUBSTR( TTOC( A6.debut ) , 12 , 5 ) AS c(5 ) )AS D06 ,; CAST(SUBSTR( TTOC( A7.debut ) , 12 , 5 ) AS c(5 ) )AS D07 ,; CAST(SUBSTR( TTOC( A8.debut ) , 12 , 5 ) AS c(5 ) )AS D08 ,; CAST(SUBSTR( TTOC( A9.debut ) , 12 , 5 ) AS c(5 ) )AS D09 ,; CAST(SUBSTR( TTOC( A10.debut ) , 12 , 5 ) AS c(5 ) )AS D10 ,; CAST(SUBSTR( TTOC( A11.debut ) , 12 , 5 ) AS c(5 ) )AS D11 ,; CAST(SUBSTR( TTOC( A12.debut ) , 12 , 5 ) AS c(5 ) )AS D12 ,; CAST(SUBSTR( TTOC( A13.debut ) , 12 , 5 ) AS c(5 ) )AS D13 ,; CAST(SUBSTR( TTOC( A14.debut ) , 12 , 5 ) AS c(5 ) )AS D14 ,; CAST(SUBSTR( TTOC( A15.debut ) , 12 , 5 ) AS c(5 ) )AS D15 ,;this Code give D02 with NULL value ?