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Input

SELECT vend_name, prod_name, prod_price

FROM vendors, products

ORDER BY vend_name, prod_name;

Output

+----------------+----------------+------------+

| vend_name | prod_name | prod_price |

+----------------+----------------+------------+

| ACME | .5 ton anvil | 5.99 |

| ACME | 1 ton anvil | 9.99 |

| ACME | 2 ton anvil | 14.99 |

| ACME | Bird seed | 10.00 |

| ACME | Carrots | 2.50 |

| ACME | Detonator | 13.00 |

| ACME | Fuses | 3.42 |

| ACME | JetPack 1000 | 35.00 |

| ACME | JetPack 2000 | 55.00 |

| ACME | Oil can | 8.99 |

| ACME | Safe | 50.00 |

| ACME | Sling | 4.49 |

| ACME | TNT (1 stick) | 2.50 |

| ACME | TNT (5 sticks) | 10.00 |

| Anvils R Us | .5 ton anvil | 5.99 |

| Anvils R Us | 1 ton anvil | 9.99 |

| Anvils R Us | 2 ton anvil | 14.99 |

| Anvils R Us | Bird seed | 10.00 |

| Anvils R Us | Carrots | 2.50 |

| Anvils R Us | Detonator | 13.00 |

| Anvils R Us | Fuses | 3.42 |

| Anvils R Us | JetPack 1000 | 35.00 |

| Anvils R Us | JetPack 2000 | 55.00 |

| Anvils R Us | Oil can | 8.99 |

| Anvils R Us | Safe | 50.00 |

| Anvils R Us | Sling | 4.49 |

| Anvils R Us | TNT (1 stick) | 2.50 |

| Anvils R Us | TNT (5 sticks) | 10.00 |

| Furball Inc. | .5 ton anvil | 5.99 |

| Furball Inc. | 1 ton anvil | 9.99 |

| Furball Inc. | 2 ton anvil | 14.99 |

| Furball Inc. | Bird seed | 10.00 |

| Furball Inc. | Carrots | 2.50 |

| Furball Inc. | Detonator | 13.00 |

| Furball Inc. | Fuses | 3.42 |

| Furball Inc. | JetPack 1000 | 35.00 |

| Furball Inc. | JetPack 2000 | 55.00 |

| Furball Inc. | Oil can | 8.99 |

| Furball Inc. | Safe | 50.00 |

| Furball Inc. | Sling | 4.49 |

| Furball Inc. | TNT (1 stick) | 2.50 |

| Furball Inc. | TNT (5 sticks) | 10.00 |

| Jet Set | .5 ton anvil | 5.99 |

| Jet Set | 1 ton anvil | 9.99 |

| Jet Set | 2 ton anvil | 14.99 |

| Jet Set | Bird seed | 10.00 |

| Jet Set | Carrots | 2.50 |

| Jet Set | Detonator | 13.00 |

| Jet Set | Fuses | 3.42 |

| Jet Set | JetPack 1000 | 35.00 |

| Jet Set | JetPack 2000 | 55.00 |

| Jet Set | Oil can | 8.99 |

| Jet Set | Safe | 50.00 |

| Jet Set | Sling | 4.49 |

| Jet Set | TNT (1 stick) | 2.50 |

| Jet Set | TNT (5 sticks) | 10.00 |

| Jouets Et Ours | .5 ton anvil | 5.99 |

| Jouets Et Ours | 1 ton anvil | 9.99 |

| Jouets Et Ours | 2 ton anvil | 14.99 |

| Jouets Et Ours | Bird seed | 10.00 |

| Jouets Et Ours | Carrots | 2.50 |

| Jouets Et Ours | Detonator | 13.00 |

| Jouets Et Ours | Fuses | 3.42 |

| Jouets Et Ours | JetPack 1000 | 35.00 |

| Jouets Et Ours | JetPack 2000 | 55.00 |

| Jouets Et Ours | Oil can | 8.99 |

| Jouets Et Ours | Safe | 50.00 |

| Jouets Et Ours | Sling | 4.49 |

| Jouets Et Ours | TNT (1 stick) | 2.50 |

| Jouets Et Ours | TNT (5 sticks) | 10.00 |

| LT Supplies | .5 ton anvil | 5.99 |

| LT Supplies | 1 ton anvil | 9.99 |

| LT Supplies | 2 ton anvil | 14.99 |

| LT Supplies | Bird seed | 10.00 |

| LT Supplies | Carrots | 2.50 |

| LT Supplies | Detonator | 13.00 |

| LT Supplies | Fuses | 3.42 |

| LT Supplies | JetPack 1000 | 35.00 |

| LT Supplies | JetPack 2000 | 55.00 |

| LT Supplies | Oil can | 8.99 |

| LT Supplies | Safe | 50.00 |

| LT Supplies | Sling | 4.49 |

| LT Supplies | TNT (1 stick) | 2.50 |

| LT Supplies | TNT (5 sticks) | 10.00 |

+----------------+----------------+------------+

Analysis

As you can see in the preceding output, the Cartesian product is seldom what you want. The data returned here has matched every product with every vendor, including products with the incorrect vendor (and even vendors with no products at all).

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Caution: Don’t Forget the WHERE Clause

Make sure all your joins have WHERE clauses, or MariaDB returns far more data than you want. Similarly, make sure your WHERE clauses are correct. An incorrect filter condition causes MariaDB to return incorrect data.

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Tip: Cross Joins

Sometimes you’ll hear the type of join that returns a Cartesian product referred to as a cross join.

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Inner Joins

The join you have been using so far is called