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3.12 Aggregate Functions /*12. Aggregate Functions*/ /* Aggregate functions are analytic functions that calculate an aggregate value based on a group 阅读全文
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/* 154.YEAR(<date>) 返回年 YEARS_BETWEEN(<date_1>, <date_2>) 返回两个日期之间年份 */ SELECT YEAR (TO_DATE ('2011-05-30', 'YYYY-MM-DD')) FROM DUMMY; --返回2 SELECT YE 阅读全文
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153. XMLEXTRACT XMLEXTRACT(<XML_document>, <XPath_query> [,<NamespaceDeclarations>]) <XML_document> Specifies an XML document of type CLOB, NCLOB, VAR 阅读全文
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/* 149.WEEK WEEK(<date>) 返回周数 WEEKDAY(<date>) 返回日期所在周天，星期1（0）~星期天(6) */ SELECT WEEK(TO_DATE('2011-05-30', 'YYYY-MM-DD')) FROM DUMMY; SELECT WEEK ('201 阅读全文
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/* 148.VAR Aggregate function: VAR( [ ALL | DISTINCT ] <expression> ) Window function: VAR( <expression> ) <window_specification> Returns the variance 阅读全文
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/* 144. UCASE UCASE(<string>) 将字符串字符转换大写 UPPER(<string>) */ SELECT UCASE ('Ant') FROM DUMMY; SELECT UPPER ('Ant') FROM DUMMY; /* 145. UMINUS UMINUS(<n 阅读全文
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/* 141.TAN TAN(<number>) 返回正切值 TANH(<number>) 返回指定数值参数的双曲正切值。 */ SELECT TAN (0.0) FROM DUMMY; SELECT TANH(1) FROM DUMMY; /* 142. 类型转换 TO_ALPHANUM(<val 阅读全文