SQL · Theory

How To Insert Values

Theory

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How To Insert Values

INSERT INTO students (roll, name, marks) VALUES (12, 'Asha', 72); adds one row. List the columns. Don’t rely on column order in the table — tomorrow someone ALTERs it.

Many rows — INSERT INTO students (roll, name, marks) VALUES (12,'Asha',72), (13,'Kabir',40); One statement, two rows.

AUTO_INCREMENT: skip that column, MySQL fills it. Duplicate PRIMARY KEY → error 1062. INSERT IGNORE skips the bad row. ON DUPLICATE KEY UPDATE changes the old row instead.

Trap — INSERT INTO students VALUES ('Asha', 12, 72) with columns in the wrong order. Trap: inserting NULL into NOT NULL.

On the example next to this theory — How To Insert Values — iNSERT adds rows. List columns explicitly for clarity.

Exam tip

INSERT INTO students (roll, name, marks) VALUES (12, 'Asha', 72);

How To Insert Values — sample query

CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT, price REAL);
INSERT INTO products (id, name, price) VALUES
  (1, 'Mouse', 499),
  (2, 'Keyboard', 999);
SELECT * FROM products;

How To Insert Values — iNSERT adds rows. List columns explicitly for clarity.

Short notes

DefINSERT INTO t (cols) VALUES (…);
RuleName columns. Multi-row VALUES (a),(b).
TrapWrong column order. Duplicate PK.

SQL · Theory

How To Insert Values

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Theory

345/439

How To Insert Values

INSERT INTO students (roll, name, marks) VALUES (12, 'Asha', 72); adds one row. List the columns. Don’t rely on column order in the table — tomorrow someone ALTERs it.

Many rows — INSERT INTO students (roll, name, marks) VALUES (12,'Asha',72), (13,'Kabir',40); One statement, two rows.

AUTO_INCREMENT: skip that column, MySQL fills it. Duplicate PRIMARY KEY → error 1062. INSERT IGNORE skips the bad row. ON DUPLICATE KEY UPDATE changes the old row instead.

Trap — INSERT INTO students VALUES ('Asha', 12, 72) with columns in the wrong order. Trap: inserting NULL into NOT NULL.

On the example next to this theory — How To Insert Values — iNSERT adds rows. List columns explicitly for clarity.

Exam tip

INSERT INTO students (roll, name, marks) VALUES (12, 'Asha', 72);

How To Insert Values — sample query

CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT, price REAL);
INSERT INTO products (id, name, price) VALUES
  (1, 'Mouse', 499),
  (2, 'Keyboard', 999);
SELECT * FROM products;

How To Insert Values — iNSERT adds rows. List columns explicitly for clarity.

Short notes

DefINSERT INTO t (cols) VALUES (…);
RuleName columns. Multi-row VALUES (a),(b).
TrapWrong column order. Duplicate PK.

How To Insert Values

How To Insert Values — sample query

Short notes

Questions

How To Insert Values

How To Insert Values — sample query

Short notes

Questions