Can anyone please help me about understanding the sql code.
SQL statement:
'SELECT
aux_values.char_value, ' +
' aux_values.float_value, ' +
' aux_values.info, ' +
' rtdb_steel_analysis.min_element * aux_values.float_value, ' +
' rtdb_steel_analysis.max_element * aux_values.float_value, ' +
' rtdb_steel_analysis.aim_element * aux_values.float_value , ' +
' rtdb_steel_analysis.est_steel_value * aux_values.float_value, ' +
' DECODE(rle0.value, null, %f, rle0.value * aux_values.float_value), ' +
' DECODE(rle1.value, null, %f, rle1.value * aux_values.float_value), ' +
' DECODE(rle2.value, null, %f, rle2.value * aux_values.float_value), ' +
' DECODE(rle3.value, null, %f, rle3.value * aux_values.float_value) ' +
'FROM aux_values, ' +
' rtdb_steel_analysis LEFT OUTER JOIN rtdb_log_elements rle0 ' +
'ON rtdb_steel_analysis.area_id = rle0.area_id ' +
'AND rtdb_steel_analysis.station_code = rle0.station_code ' +
'AND rtdb_steel_analysis.element_id = rle0.element_id ' +
'AND rle0.analysis_counter = %d ' + ' LEFT OUTER JOIN rtdb_log_elements rle1 ' +
'ON rtdb_steel_analysis.area_id = rle1.area_id ' +
'AND rtdb_steel_analysis.station_code = rle1.station_code ' +
'AND rtdb_steel_analysis.element_id = rle1.element_id ' +
'AND rle1.analysis_counter = %d ' + ' LEFT OUTER JOIN rtdb_log_elements rle2 ' +
'ON rtdb_steel_analysis.area_id = rle2.area_id ' +
'AND rtdb_steel_analysis.station_code = rle2.station_code ' +
'AND rtdb_steel_analysis.element_id = rle2.element_id ' +
'AND rle2.analysis_counter = %d ' + ' LEFT OUTER JOIN rtdb_log_elements rle3 ' +
'ON rtdb_steel_analysis.area_id = rle3.area_id ' +
'AND rtdb_steel_analysis.station_code = rle3.station_code ' +
'AND rtdb_steel_analysis.element_id = rle3.element_id ' +
'AND rle3.analysis_counter = %d ' + 'WHERE aux_values.variable_id = %s ' +
'AND aux_values.integer_value = rtdb_steel_analysis.element_id ' +
'AND rtdb_steel_analysis.area_id = %d ' +
'AND rtdb_steel_analysis.station_code = %d ' +
'AND rtdb_steel_analysis.step_seq = %d ' +
'AND rtdb_steel_analysis.max_element > %f ' +
'ORDER BY aux_values.value_seq ' ;
this code is written in Delphi IDE. But problem is i am unable to understand the 9th line ' DECODE(rle0.value, null, %f, rle0.value * aux_values.float_value), ' +. Please help to understand this.