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现在有两个关系模式：供应商S(Sno，Sname，Status，City)和供应情况SPJ(Sno，Pno，Jno， Qty)。对于查询“查询零件号Pno等于‘P3’的供应商名Sname”SQL语句(221)是错误的，而关系代数表达式(222)是正确的。
A．SELECTSname FROM S WHERE EXIST5(SELECT * FROM SPJ WHERE S.Sno＝SPJ.Sno AND SPJ.Pno＝'P3')
B．SELECT Sname FROM S,SPJ WHERE S.Sno＝SPJ.Sno AND SPJ.Pno＝'P3') CROUP BY Sname
C．SELECT DISTINCT Sname FROM S WHERE EXISTS(SELECT * FROM SPJ WHERE S.Sno＝SPJ.Sno AND SPJ.Pno＝'P3')
D．SELECT DISTINCT Sname FROM S WHERERE 0＜(SELECTCOUNT(，) FROM SPJ WHERE S.Sno＝SPJ.Sno AND SPJ.Pnn＝'P3')
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更多 “ 现在有两个关系模式：供应商S(Sno，Sname，Status，City)和供应情况SPJ(Sno，Pno，Jno， Qty)。对于查询“查询零件号Pno等于‘P3’的供应商名Sname”SQL语句(221)是错误的，而关系代数表达式(222)是正确的。A．SELECTSname FROM S WHERE EXIST5(SELECT * FROM SPJ WHERE S.Sno＝SPJ.Sno AND SPJ.Pno＝'P3')B．SELECT Sname FROM S,SPJ WHERE S.Sno＝SPJ.Sno AND SPJ.Pno＝'P3') CROUP BY SnameC．SELECT DISTINCT Sname FROM S WHERE EXISTS(SELECT * FROM SPJ WHERE S.Sno＝SPJ.Sno AND SPJ.Pno＝'P3')D．SELECT DISTINCT Sname FROM S WHERERE 0＜(SELECTCOUNT(，) FROM SPJ WHERE S.Sno＝SPJ.Sno AND SPJ.Pnn＝'P3') ” 相关考题
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