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COUNT º¯Êý¿ÉÅÌËã±íÖÐÖظ´ÖµµÄÊýÄ¿¡£Óï·¨£º

COUNT(column_name)

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SELECT COUNT(city) FROM customers WHERE city = 'New York';

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GROUP BY ×Ó¾ä¿É½«Êý¾Ý·Ö×飬ȻºóÓ¦ÓþۺϺ¯Êý£¨Èç COUNT£©ÅÌËãÿ¸ö×éÖеÄÖµ¡£Óï·¨£º

SELECT column_name, COUNT(*)
FROM table_name
GROUP BY column_name

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ÈôÒªÕÒ³ö “customers” ±íÖа´¶¼»á·Ö×éµÄ¿Í»§ÊýÄ¿£º

SELECT city, COUNT(*) AS customer_count
FROM customers
GROUP BY city;

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FROM table_name
GROUP BY column_name
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ÈôÒªÕÒ³ö “customers” ±íÖпͻ§ÊýÄ¿´óÓÚ 500 ¸öµÄ¶¼»á£º

SELECT city, COUNT(*) AS customer_count
FROM customers
GROUP BY city
HAVING customer_count > 500;

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