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The original link⭐MybatisPlus learning ⭐ (2) CRUD full set of detailed explanation

Look at the MybatisPlus module for this link

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1. Mapper CRUD interface

Description:

• The universal CRUD encapsulates the BaseMapper interface for Mybatis-Plus to automatically parse the entity table relational mapping when started into Mybatis internal object injection container
• The generic T is any entity object
• Mybatis-Plus is not recommended to use the compound primary key convention. Each table has its own unique primary key id
• Object Wrapper is a conditional constructor

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1.1, the Insert

// Insert a record
int insert(T entity);
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== Parameter Description ==

type	Parameter names	describe
T	entity	Entity objects

Employee employee = new Employee();
employee.setLastName("Mantis shrimp");
employee.setAge(21);
employee.setEmail("[email protected]");
employee.setGender(1);

employeeMapper.insert(employee);
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1.2, Delete

// Delete the record based on the entity condition
int delete(@Param(Constants.WRAPPER) Wrapper<T> wrapper);
// Delete (batch delete based on ID)
int deleteBatchIds(@Param(Constants.COLLECTION) Collection<? extends Serializable> idList);
// Delete based on ID
int deleteById(Serializable id);
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== Parameter Description ==

type	Parameter names	describe
Wrapper	wrapper	Entity object encapsulates operation class (can be null)
Collection<? extends Serializable>	idList	List of primary key ids (not null or EMPTY)
Serializable	id	The primary key ID
Map<String, Object>	columnMap	Table field map object

1.3, the Update

// Modify according to the ID
int updateById(@Param(Constants.ENTITY) T entity);
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== Parameter Description ==

type	Parameter names	describe
T	entity	Entity object (set conditional value, can be null)
Wrapper	updateWrapper	Entity object encapsulates operation class (can be null, where entity is used to generate WHERE statement)

1.4, the Select

// Query by ID
T selectById(Serializable id);
// Query a record based on the entity condition
T selectOne(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);

// Query (batch query based on ID)
List<T> selectBatchIds(@Param(Constants.COLLECTION) Collection<? extends Serializable> idList);
// Query all records based on the entity condition
List<T> selectList(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);

// Query the total number of records according to the Wrapper condition
Integer selectCount(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
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== Parameter Description ==

type	Parameter names	describe
Serializable	id	The primary key ID
Wrapper	queryWrapper	Entity object encapsulates operation class (can be null)
Collection<? extends Serializable>	idList	List of primary key ids (not null or EMPTY)
Map<String, Object>	columnMap	Table field map object
IPage	page	Paging query criteria (can be rowbound.default)

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2. Service CRUD interface

= = = = :

• Use Service CRUD to encapsulate IService interface, and further encapsulate CRUD. Use GET query single row remove delete list query set Page paging prefix to distinguish Mapper layer to avoid confusion.
• The generic T is any entity object
• If custom generic Service methods are possible, create your own IBaseService that inherits from the base class provided by Mybatis Plus
• Object Wrapper is a conditional constructor

== Create Service and implementation class ==

EmployeeService

public interface EmployeeService extends IService<Employee> {}Copy the code

EmployeeImpl

@Service
public class EmployeeImpl extends ServiceImpl<EmployeeMapper.Employee> implements EmployeeService {}Copy the code

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2.1, Save

// Insert a record (select field, policy insert)
boolean save(T entity);
// Insert (batch)
boolean saveBatch(Collection<T> entityList);
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== Parameter Description ==

type	Parameter names	describe
T	entity	Entity objects
Collection	entityList	Entity object collection
int	batchSize	Number of insert batches

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2.2, SaveOrUpdate

// Insert a new record in TableId
boolean saveOrUpdate(T entity);
// Batch modify inserts
boolean saveOrUpdateBatch(Collection<T> entityList);
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== Parameter Description ==

type	Parameter names	describe
T	entity	Entity objects
Wrapper	updateWrapper	Entity object wrapper operation class UpdateWrapper
Collection	entityList	Entity object collection
int	batchSize	Number of insert batches

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2.3, Remove

// Delete the record based on the entity condition
boolean remove(Wrapper<T> queryWrapper);
// Delete based on ID
boolean removeById(Serializable id);
// Delete (batch delete based on ID)
boolean removeByIds(Collection<? extends Serializable> idList);
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== Parameter Description ==

type	Parameter names	describe
Wrapper	queryWrapper	Physical wrapper class QueryWrapper
Serializable	id	The primary key ID
Map<String, Object>	columnMap	Table field map object
Collection<? extends Serializable>	idList	List of primary key ids

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2.4, the Update

// Select modify according to the ID
boolean updateById(T entity);
// Batch update based on ID
boolean updateBatchById(Collection<T> entityList);
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== Parameter Description ==

type	Parameter names	describe
Wrapper	queryWrapper	Physical wrapper class QueryWrapper
T	entity	Entity objects
Collection	entityList	Entity object collection
int	batchSize	Update batch number

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2.5, the Get

// Query by ID
T getById(Serializable id);
// Query a record from the Wrapper
T getOne(Wrapper<T> queryWrapper, boolean throwEx);
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== Parameter Description ==

type	Parameter names	describe
Serializable	id	Primary key ID of the physical wrapper class
T	entity	Entity objects
Collection	entityList	Entity object collection
Function<? super Object, V>	mapper	The transition function
Wrapper	queryWrapper	Entity object wrapper operation class QueryWrapper

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2.6, the List

// Query all
List<T> list(a);
// Query the list
List<T> list(Wrapper<T> queryWrapper);
// Query (batch query based on ID)
Collection<T> listByIds(Collection<? extends Serializable> idList);
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== Parameter Description ==

type	Parameter names	describe
Collection<? extends Serializable>	idList	List of primary key ids
Map<? String, Object>	columnMap	Table field map object
Collection	entityList	Entity object collection
Function<? super Object, V>	mapper	The transition function
Wrapper	queryWrapper	Entity object wrapper operation class QueryWrapper

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2.7, the Count

// Query the total number of records
int count(a);
// Query the total number of records according to the Wrapper condition
int count(Wrapper<T> queryWrapper);
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== Parameter Description ==

type	Parameter names	describe
Wrapper	queryWrapper	Entity object wrapper operation class QueryWrapper

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The last

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