多项选择题
A. TRIM B. REPLACE C. TRUNC D. TO_DATE E. MOD F. CASE
Which three are true?（）A. A MERGE statement is used to ...
多项选择题Which three are true?（）
A. A MERGE statement is used to merge the data of one table with data from another. B. A MERGE statement replaces the data of one table with that of another. C. A MERGE statement can be used to insert new rows into a table. D. A MERGE statement can be used to update existing rows in a table.
Evaluate this SQL statement: In the statement, which c...
单项选择题
Evaluate this SQL statement: In the statement, which capabilities of a SELECT statement are performed?（）
A. Selection, projection, join B. Difference, projection, join C. Selection, intersection, join D. Intersection, projection, join E. Difference, projection, product
Which two statements are true about constraints? （）A. T...
多项选择题Which two statements are true about constraints? （）
A. The UNIQUE constraint does not permit a null value for the column. B. A UNIQUE index gets created for columns with PRIMARY KEY and UNIQUE constraints. C. The PRIMARY KEY and FOREIGN KEY constraints create a UNIQUE index. D. The NOT NULL constraint ensures that null values are not permitted for the column.
