Statement: there were no directors that directed more than one episode

Input Table: list of republic of doyle episodes

Step 1: Select rows where 'directed_by' is not null.
unnamed__0 title directed_by written_by viewers original_airdate prod_code
1 fathers and sons mike clattenburg allan hawco , perry chafe and malcolm macrury 969000 2010-01-06 101
2 the return of the grievous angel steve dimarco allan hawco and avrum jacobson 715000 2010-01-13 102
3 duchess of george mike clattenburg allan hawco , perry chafe and malcolm macrury 685000 2010-01-20 103
5 hit and rum steve dimarco matt maclennan 594000 2010-02-03 105
6 the one who got away larry mclean jesse mckeown 1012000 2010-02-10 106
7 the woman who knew too little robert lieberman jeremy boxen 1053000 2010-03-03 107
8 the tell - tale safe jerry ciccoritti john callaghan and steve cochrane 986000 2010-03-10 108
9 he sleeps with the chips phil earnshaw perry chafe 908000 2010-03-17 109
10 the pen is mightier than the doyle robert lieberman steve cochrane and avrum jacobson 897000 2010-03-24 110
11 a horse divided steve scaini jesse mckeown 902000 2010-03-31 111
Step 2: Group the table by 'directed_by' and count the number of unique values in 'directed_by'.
unnamed__0 title directed_by written_by viewers original_airdate prod_code
1 fathers and sons mike clattenburg allan hawco , perry chafe and malcolm macrury 969000 2010-01-06 101
2 the return of the grievous angel steve dimarco allan hawco and avrum jacobson 715000 2010-01-13 102
3 duchess of george mike clattenburg allan hawco , perry chafe and malcolm macrury 685000 2010-01-20 103
5 hit and rum steve dimarco matt maclennan 594000 2010-02-03 105
6 the one who got away larry mclean jesse mckeown 1012000 2010-02-10 106
7 the woman who knew too little robert lieberman jeremy boxen 1053000 2010-03-03 107
8 the tell - tale safe jerry ciccoritti john callaghan and steve cochrane 986000 2010-03-10 108
9 he sleeps with the chips phil earnshaw perry chafe 908000 2010-03-17 109
10 the pen is mightier than the doyle robert lieberman steve cochrane and avrum jacobson 897000 2010-03-24 110
11 a horse divided steve scaini jesse mckeown 902000 2010-03-31 111
Step 3: Use a `CASE` statement to return TRUE if the number of unique values is equal to the number of rows, otherwise return FALSE.
directed_by unique_directors
jerry ciccoritti 1
larry mclean 1
mike clattenburg 1
phil earnshaw 1
robert lieberman 1
steve dimarco 1
steve scaini 1
Final output table:
verification_result
TRUE

Prediction: TRUE