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95 lines
2.3 KiB
Markdown
95 lines
2.3 KiB
Markdown
# Db + Row 工具的使用
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Db + Row 工具类，提供了在 Entity 实体类之外的数据库操作能力。使用 Db + Row 时，无需对数据库表进行映射， Row 是一个 HashMap 的子类，相当于一个通用的 Entity。以下为 Db + Row 的一些示例：
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```java
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//使用原生 SQL 插入数据
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String sql = "insert into tb_account(id,name) value (?, ?)";
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Db.insertBySql(sql,1,"michael");
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//使用 Row 插入数据
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Row account = new Row();
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account.set("id",100);
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account.set(ACCOUNT.USER_NAME,"Michael");
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Db.insert("tb_account",account);
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//根据主键查询数据
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Row row = Db.selectOneById("tb_account","id",1);
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//Row 可以直接转换为 Entity 实体类，且性能极高
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Account account = row.toEntity(Account.class);
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//查询所有大于 18 岁的用户
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String listsql = "select * from tb_account where age > ?"
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List<Row> rows = Db.selectListBySql(sql,18);
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//分页查询：每页 10 条数据，查询第 3 页的年龄大于 18 的用户
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QueryWrapper query = QueryWrapper.create()
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.where(ACCOUNT.AGE.ge(18));
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Page<Row> rowPage = Db.paginate("tb_account",3,10,query);
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```
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> Db 工具类还提供了更多 增、删、改、查和分页查询等方法。
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>
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> 具体参考： [Db.java](./mybatis-flex-core/src/main/java/com/mybatisflex/core/row/Db.java) 。
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## Row 转换为 Entity
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```java
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Row row = Db.selectOneById("tb_account","id",1);
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Account entity = row.toEntity(Account.class);
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```
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## Row 字段转化为驼峰风格
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```java
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Row row = Db.selectOneById("tb_account","id",1);
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Map result = row.toCamelKeysMap();
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```
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## Row 字段转换为下划线风格
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```java
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Row row = Db.selectOneById("tb_account","id",1);
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Map result = row.toUnderlineKeysMap();
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```
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## Row 插入时，设置主键生成方式
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**ID 自增**
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```java
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// ID 自增
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Row row = Row.ofKey(RowKey.ID_AUTO);
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row.set(ACCOUNT.USER_NAME,"Michael");
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Db.insert("tb_account",row);
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```
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**ID 为 UUID**
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```java
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// ID 为 uuid
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Row row = Row.ofKey(RowKey.ID_UUID);
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row.set(ACCOUNT.USER_NAME,"Michael");
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Db.insert("tb_account",row);
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```
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**自定义 Row 主键生成方式**
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```java
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// 自定义 Row Key，整个应用定义一个常量即可
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RowKey myRowKey = RowKey.of("id", KeyType.Generator, "uuid", true);
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// 使用自定义的 RowKey
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Row row = Row.ofKey(myRowKey);
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row.set(ACCOUNT.USER_NAME,"Michael");
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Db.insert("tb_account",row);
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```
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