cau1.tao bang 7 cot 6 hang ->vao table->insert->table. o number of columns, go 7.o number of rows, go 6.bam ok cau2.chen them 2 cot giua cot 4 va cot 5->chon cot 4, vao table->insert->column to the right, thao tac lai 1 lan nua cau3. xoa hang 5,6->chon hang 5,6.vao table->delete->rows.xog
