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Update README for Preload

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Jinzhu 2015-02-11 19:27:58 +08:00
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README.md
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@ -12,6 +12,7 @@ The fantastic ORM library for Golang, aims to be developer friendly.
* Callbacks (before/after create/save/update/delete/find)
* Soft Deletes
* Auto Migrations
* Preloading (eager loading)
* Transactions
* Customizable Logger
* Iteration Support via [Rows](#row--rows)
@ -335,6 +336,28 @@ db.Where("name <> ?","jinzhu").Where("age >= ? and role <> ?",20,"admin").Find(&
db.Where("role = ?", "admin").Or("role = ?", "super_admin").Not("name = ?", "jinzhu").Find(&users)
```
### Preloading (Eager loading)
```go
db.Preload("Orders").Find(&users)
//// SELECT * FROM users;
//// SELECT * FROM orders WHERE user_id IN (1,2,3,4);
db.Preload("Orders", "state NOT IN (?)", "cancelled").Find(&users)
//// SELECT * FROM users;
//// SELECT * FROM orders WHERE user_id IN (1,2,3,4) AND state NOT IN ('cancelled');
db.Where("state = ?", "active").Preload("Orders", "state NOT IN (?)", "cancelled").Find(&users)
//// SELECT * FROM users WHERE state = 'active';
//// SELECT * FROM orders WHERE user_id IN (1,2) AND state NOT IN ('cancelled');
db.Preload("Orders").Preload("Profile").Preload("Role").Find(&users)
//// SELECT * FROM users;
//// SELECT * FROM orders WHERE user_id IN (1,2,3,4); // has many
//// SELECT * FROM profiles WHERE user_id IN (1,2,3,4); // has one
//// SELECT * FROM roles WHERE id IN (4,5,6); // belongs to
```
## Update
```go