. . . R07109 Ivanov I.I. 01.01.78 R07109 Math. Analysis 5 950 М R07110 P.P. 23.02.78 R07110 Math. Analysis 4 900 М R07112 Sidorova 8.03.79 F R07112 Math. Analysis 5 1000 Е.I. . . . R07109 Ivanov I.I. 01.01.78 R07109 Programming 5 980 М R07110 Peter P.P. 23.02.78 R07110 Programming 5 950 М R07112 Sidorova 8.03.79 F R07112 Programming 4 850 Е.I. . . . R07109 Ivanov I.I. 01.01.78 R07109 DB and KB 4 850 М R07110 Peter P.P. 23.02.78 R07110 DB and KB 5 980 М R07112 Sidorova 8.03.79 F R07112 DB and KB 4 800 Е.I. Fig. 3.2.1.7 Physically this file does not exist, but for the program processing all the operations may be performed as if it were a real file. As the relational fields several fields may be used. So the second file may be related with the following ones (Fig. 3.2.1.8) by the fields: student number and subject. Student # Subject Month Absence Quantity Attestation score . . . R07109 Math. Analysis September 10 5 R07110 Math. Analysis September 0 5 R07112 Math. Analysis September 40 3 . . . R07109 Math. Analysis October 6 4 Math. Analysis October 16 4 Р07110 R07112 Math. Analysis October 0 5 . . . R07109 Programming December 0 5 R07110 Programming December 20 3 R07112 Programming December 10 5 . . . R07109 DB and KB February 0 5 R07110 DB and KB February 6 4 DB and KB February 8 5 Р07112 . . . DB and KB May 6 5 Р07109
. . . R07109 Ivanov I.I. 01.01.78 М R07109 Math. Analysis 5 950 R07110 P.P. 23.02.78 М R07110 Math. Analysis 4 900 R07112 Sidorova Е.I. 8.03.79 F R07112 Math. Analysis 5 1000 . . . R07109 Ivanov I.I. 01.01.78 М R07109 Programming 5 980 R07110 Peter P.P. 23.02.78 М R07110 Programming 5 950 R07112 Sidorova Е.I. 8.03.79 F R07112 Programming 4 850 . . . R07109 Ivanov I.I. 01.01.78 М R07109 DB and KB 4 850 R07110 Peter P.P. 23.02.78 М R07110 DB and KB 5 980 R07112 Sidorova Е.I. 8.03.79 F R07112 DB and KB 4 800 Fig. 3.2.1.7 Physically this file does not exist, but for the program processing all the operations may be performed as if it were a real file. As the relational fields several fields may be used. So the second file may be related with the following ones (Fig. 3.2.1.8) by the fields: student number and subject. Student # Subject Month Absence Quantity Attestation score . . . R07109 Math. Analysis September 10 5 R07110 Math. Analysis September 0 5 R07112 Math. Analysis September 40 3 . . . R07109 Math. Analysis October 6 4 Р07110 Math. Analysis October 16 4 R07112 Math. Analysis October 0 5 . . . R07109 Programming December 0 5 R07110 Programming December 20 3 R07112 Programming December 10 5 . . . R07109 DB and KB February 0 5 R07110 DB and KB February 6 4 Р07112 DB and KB February 8 5 . . . Р07109 DB and KB May 6 5
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