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SELECT Count(*) AS UniqueCount FROM (SELECT DISTINCT Name FROM table1) AS UniqueNames;
? ?? ??? ?? ??? ???? ?? Name?? ??? table1 ?? ?????. ?? ?? ?? ??? ? ?? ?? ??? ? ?? ???? ?? ??? ???? ?????.
??:
??? ??? ??? table1:
| ID | Name | Family |
|---|---|---|
| 1 | A | AA |
| 2 | B | BB |
| 3 | A | AB |
| 4 | D | DD |
| 5 | E | EE |
| 6 | A | AC |
?? ??:
SELECT Count(*) AS UniqueCount FROM (SELECT DISTINCT Name FROM table1) AS UniqueNames;
??:
<code>+-------------+ | UniqueCount | +-------------+ | 4 | +-------------+</code>
??? ?? ??(A, B, D, E)? ??? ??? ???? ?????. ? ??? Access ??????? ?? ?? ???? ?? ???? ??? ???? ?????.
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