68 lines
1.5 KiB
Markdown
68 lines
1.5 KiB
Markdown
# Creating query
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```cpp
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auto q = db.posts().query();
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```
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You can also create query in one command:
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```cpp
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auto result = db.posts().query()
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->where(Post::idField() == 1)
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->toList();
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```
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Now, _result_ contains **QList\<QSharedPointer\<Post\>\>** and can be used in code. query has other commands like: sum, avg, max, min and etc
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## Getting first record in query
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```cpp
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auto post = db.posts().query()
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->setWhere(Post::idField() == 1)
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->first();
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if(post)
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qDebug() << "Post found in database";
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else
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qDebug() << "No post found!";
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```
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## Sorting result
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```cpp
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auto posts = db.posts().query()
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->where(Post::idField() == 1)
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->orderBy(Post::idField())
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->toList();
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```
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Also, you can sort descending by adding **!** to field name
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```cpp
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auto posts = db.posts().query()
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->where(Post::idField() == 1)
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->orderBy(!Post::idField())
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->toList();
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```
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## Selecting single field
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```cpp
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auto ids = db.posts().query()
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->select(Post::idField());
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//ids is type of QList<int>
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```
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## Getting sum, count, min, max
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```cpp
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auto q = db.posts().query();
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auto sum = q.sum(Post::idField());
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auto max = q.max(Post::idField());
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auto min = q.min(Post::idField());
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auto count = q.count(Post::idField());
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```
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## Checking field exists in list of values
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```cpp
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auto post = db.posts().query()
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->where(Post::idField().in(QList<int>() << 1 << 2 << 3 << 4) || Post::isAccepted())
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->first();
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```
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Or
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```cpp
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auto post = db.posts().query()
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->where(Post::idField().in({1, 2, 3, 4}) || Post::isAccepted())
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->first();
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```
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