# Multi-Table Join Analysis (Continued...)

+ Create indexes for the columns of the driven table that involve joins:

```12
ALTER TABLE t2 ADD INDEX idx_k(k);
```

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The optimization of the driving table here is to make the table join use the index as much as possible. Unless the k column is very repetitive, you only need to add an index on the join column k field to ensure that the index can be used when the table is joined: ALTER TABLE t2 ADD INDEX idx_k (k);.