A. SELECT*FROM商品WHERE类型="电器"AND名称LIKE"照相机" B. SELECT*FROM商品WHERE类型="电器"OR名称LIKE"照相机" C. SELECT*FROM商品WHERE类型="电器"AND名称="照相机" D. SELECT*FROM商品WHERE类型="电器"AND名称LIKE"*照相机*"
A. CREATETABLE B. ALTERTABLE C. DROP D. CREATEINDEX
All B. ORDER C. TOP DISTINCT
A. m+1 B. m+2 C. t+1 D. t+2