1.What is the main purpose of the ALTER statement in SQL?
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A. To delete tables
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B. To modify an existing database object
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C. To insert new rows
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D. To create a new table
To modify an existing database object
To modify an existing database object
2.Which SQL keyword is used to add a new column to an existing table?
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A. MODIFY COLUMN
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B. UPDATE COLUMN
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C. INSERT COLUMN
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D. ADD COLUMN
ADD COLUMN
ADD COLUMN
3.Which of the following is the correct syntax to rename a column in PostgreSQL?
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A. ALTER TABLE table_name RENAME COLUMN old TO new;
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B. RENAME COLUMN old TO new;
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C. ALTER COLUMN old RENAME TO new;
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D. ALTER TABLE table_name CHANGE old new;
ALTER TABLE table_name RENAME COLUMN old TO new;
ALTER TABLE table_name RENAME COLUMN old TO new;
4.In MySQL, what is the correct way to change a column’s data type?
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A. ALTER TABLE table_name ALTER COLUMN col_name TYPE new_type;
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B. ALTER TABLE table_name CHANGE col_name col_name new_type;
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C. ALTER TABLE table_name MODIFY COLUMN col_name new_type;
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D. Both B and C
Both B and C
Both B and C
5.Which clause is used to drop a column from an existing table?
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A. ALTER TABLE table_name REMOVE COLUMN col_name;
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B. DROP COLUMN col_name;
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C. ALTER TABLE table_name DROP col_name;
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D. ALTER TABLE table_name DROP COLUMN col_name;
ALTER TABLE table_name DROP COLUMN col_name;
ALTER TABLE table_name DROP COLUMN col_name;