It performs a merge join of the row from T2 only if it doesn’t exist in the T1 table.
It creates a natural join of tables T1 and T2 for all columns that have the same name.
It creates a Cartesian product of table T1 and table T2 for all columns that have the same name.
For each row from T2, it updates the row if it exists within table T1, otherwise it inserts the row into T1.
第1题:
第2题:
Which two statements are true regarding the USING clause in table joins?()
第3题:
下面不属于同一函数模板的是( )。
A.template<class t1> t1 max(t1 &a,t1 &b) {…}template<class t2> t2 max(t2 &a,t2 &b) {…}
B.template<class t1>t1 max(t1 a,t1 b){…}template<class t2>t2 max(t2 &a,t2 &b){…}
C.template<class t1> t1 max(t1 * a,t1 * b) {…} template<class t2> t2 max(t2 &a,t2 &b) {…}
D.template<class t1>t1 max(t1 a,t1 b){…}template<class t2>t2 max(t2 &a,t2 &b,t2 c){…}
第4题:
脑脊液MRI检查是()
第5题:
下面哪个调度是串行调度()。
第6题:
同一组织T1与T2值的关系是()。
第7题:
在下列模板说明中,正确的是()
第8题:
A.SELECT * FROM t1 UNION SELECT * FROM t2
B.SELECT * FROM t1 UNION DISTINCT SELECT * FROM t2
C.SELECT * FROM t1 INTERSECT SELECT * FROM t2
D.SELECT * FROM t1 WHERE (c1,c2)= (SELECT c1,c2 FROM t2)
第9题:
高浓度顺磁造影剂对质子弛豫时间的影响为()。
第10题:
脊髓呈()