设有关系R(A，B，C)，与SQL语句“Select distinct A from R Where B=17；”等价的关系代数表达式为_____。
A: [img=50x22]18034306a54bd7d.png[/img]
B: [img=73x22]18034306aeb0ce7.png[/img]
C: [img=112x20]18034306b7cc109.png[/img]
D: [img=111x23]18034306bf9abb8.png[/img]
A: [img=50x22]18034306a54bd7d.png[/img]
B: [img=73x22]18034306aeb0ce7.png[/img]
C: [img=112x20]18034306b7cc109.png[/img]
D: [img=111x23]18034306bf9abb8.png[/img]
举一反三
- 设有关系R(A，B，C)，与SQL语句“Select distinct A from R Where B=17；”等价的关系代数表达式为_____。 A: [img=112x20]1803c72a18badba.png[/img] B: [img=50x22]1803c72a21a479b.png[/img] C: [img=73x22]1803c72a2972d8f.png[/img] D: [img=111x23]1803c72a317b53c.png[/img]
- 设有关系R(A，B，C)，与SQL语句“Select distinct A from R Where B=17；”等价的关系代数表达式为_____。 A: [img=50x22]18030b11d2f5118.png[/img] B: [img=73x22]18030b11dabded7.png[/img] C: [img=112x20]18030b11e2d76f2.png[/img] D: [img=111x23]18030b11ead43f6.png[/img]
- 设有关系R(A，B，C)，与SQL语句“Select distinct A from R Where B=17；”等价的关系代数表达式为_____。 A: [img=112x20]1802ebc482f5683.png[/img] B: [img=50x22]1802ebc48b2268b.png[/img] C: [img=73x22]1802ebc4934f235.png[/img] D: [img=111x23]1802ebc49b60077.png[/img]
- 设有关系R(A，B，C)，与SQL语句“Select distinct A from R Where B=17；”等价的关系代数表达式为_____。 A: [img=112x20]18030b12a676de3.png[/img] B: [img=50x22]18030b12af29d3f.png[/img] C: [img=73x22]18030b12b6f26af.png[/img] D: [img=111x23]18030b12bfdcb84.png[/img]
- 设有关系R(A，B，C)，与SQL语句“Select distinct A from R Where B=17；”等价的关系代数表达式为_____。 A: [img=112x20]1803a873f3e9eef.png[/img] B: [img=50x22]1803a873fb9a06c.png[/img] C: [img=73x22]1803a874035458a.png[/img] D: [img=111x23]1803a8740c0e096.png[/img]