WCDB 是一个高效、完整、易用的移动数据库框架，基于 SQLCipher，支持 iOS, macOS 和 Android。
本文简单记录 WCDB 在 Objective-C 项目下的使用代码。
类字段绑定（ORM）
Message.h
#import <Foundation/Foundation.h>
@interface Message : NSObject
@property (nonatomic, assign) int localID;
@property (nonatomic, copy) NSString *content;
@property (nonatomic, retain) NSDate *createTime;
@property (nonatomic, retain) NSDate *modifiedTime;
@property (nonatomic, assign) int unused; // You can only define the properties you need
@endMessage.mm
#import "Message.h"
#import <WCDB/WCDB.h>
@implementation Message
// 使用 WCDB_IMPLEMENTATION 宏在「类文件」定义绑定到数据库表的类
WCDB_IMPLEMENTATION(Message)
// 绑定字段
// 使用 WCDB_SYNTHESIZE 宏在类文件定义需要绑定到数据库表的字段
WCDB_SYNTHESIZE(Message, localID)
WCDB_SYNTHESIZE(Message, content)
WCDB_SYNTHESIZE(Message, createTime)
WCDB_SYNTHESIZE(Message, modifiedTime)
// 将数据库表的字段与类的属性名进行映射
// WCDB_SYNTHESIZE_COLUMN(Message, localID, "db_id")
// WCDB_SYNTHESIZE_COLUMN(Message, content, "db_content")
// WCDB_PRIMARY 定义主键
WCDB_PRIMARY(Message, localID)
// WCDB_PRIMARY_AUTO_INCREMENT 定义主键且自增
// Auto-increment 会在新记录插入表中时生成一个唯一的数字。
//WCDB_PRIMARY_AUTO_INCREMENT(Message, localID)
// WCDB_INDEX 定义索引
// 索引：CREATE INDEX message_index ON message(createTime)
WCDB_INDEX(Message, "_index", createTime)
// WCDB_UNIQUE 定义唯一约束
// WCDB_UNIQUE(<#className#>, <#propertyName#>)
// WCDB_NOT_NULL 定义非空约束
// WCDB_NOT_NULL(<#className#>, <#propertyName#>)
@endMessage+WCTTableCoding.h
#import "Message.h"
#import <WCDB/WCDB.h>
@interface Message (WCTTableCoding) <WCTTableCoding>
// 使用 WCDB_PROPERTY 宏在「头文件」中声明需要绑定到数据库表的字段
WCDB_PROPERTY(localID)
WCDB_PROPERTY(content)
WCDB_PROPERTY(createTime)
WCDB_PROPERTY(modifiedTime)
@end创建表和索引
- (void)setupDatabase {
NSURL *databaseURL = [self p_userDatabaseURL];
self.database = [[WCTDatabase alloc] initWithPath:databaseURL.path];
BOOL result = [self.database createTableAndIndexesOfName:kTableName withClass:IMUser.class];
NSAssert(result, @"Failed to Create users Database.");
}
// ./Documents/User/%ld/Database/common/user.sqlite
- (NSURL *)p_userDatabaseURL {
NSFileManager *fileManager = [NSFileManager defaultManager];
NSURL *documentsURL = [fileManager URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask].firstObject;
NSString *directory = [NSString stringWithFormat:@"User/%ld/Database/common/", (long)_userId];
NSURL *directoryURL = [documentsURL URLByAppendingPathComponent:directory];
if (![fileManager fileExistsAtPath:directoryURL.path]) {
BOOL result = [fileManager createDirectoryAtPath:directoryURL.path withIntermediateDirectories:YES attributes:nil error:nil];
NSAssert(result, @"Failed to Create Directory: %@.",directoryURL.path);
}
return [directoryURL URLByAppendingPathComponent:@"user.sqlite"];
}增删查改
插入
insertObject:into:和insertObjects:into:，插入单个或多个对象insertOrReplaceObject:into和insertOrReplaceObjects:into，插入单个或多个对象。当对象的主键在数据库内已经存在时，更新数据；否则插入对象。insertObject:onProperties:into:和insertObjects:onProperties:into:，插入单个或多个对象的部分属性insertOrReplaceObject:onProperties:into和insertOrReplaceObjects:onProperties:into，插入单个或多个对象的部分属性。当对象的主键在数据库内已经存在时，更新数据；否则插入对象。
Message *message = [[Message alloc] init];
message.localID = 1;
message.content = @"Hello WCDB!";
message.createTime = [NSDate date];
message.modifiedTime = [NSDate date];
/**
INSERT INTO message(localID, content, createTime, modifiedTime)
VALUES(1, "Hello WCDB!", 1496396165, 1496396165);
*/
BOOL result = [database insertObject:message
into:@"message"];
// INSERT INTO message(localID, content) VALUES(?,?);
BOOL result = [database insertObject:message
onProperties:{Message.localID, Message.content}
into:@"message"];
//Insert one object
{
WCTSampleConvenient *object = [[WCTSampleConvenient alloc] init];
object.intValue = 1;
object.stringValue = @"Insert one object";
[database insertObject:object
into:tableName];
}
//Insert objects
{
NSMutableArray *objects = [[NSMutableArray alloc] init];
WCTSampleConvenient *object1 = [[WCTSampleConvenient alloc] init];
object1.intValue = 2;
object1.stringValue = @"Insert objects";
[objects addObject:object1];
WCTSampleConvenient *object2 = [[WCTSampleConvenient alloc] init];
object2.intValue = 3;
object2.stringValue = @"Insert objects";
[objects addObject:object2];
[database insertObjects:objects
into:tableName];
}
//Insert or replace one object
{
WCTSampleConvenient *object = [[WCTSampleConvenient alloc] init];
object.intValue = 1;
object.stringValue = @"Insert or replace one object";
[database insertOrReplaceObject:object
into:tableName];
}
//Insert or replace objects
{
NSMutableArray *objects = [[NSMutableArray alloc] init];
WCTSampleConvenient *object1 = [[WCTSampleConvenient alloc] init];
object1.intValue = 2;
object1.stringValue = @"Insert or replace objects";
[objects addObject:object1];
WCTSampleConvenient *object2 = [[WCTSampleConvenient alloc] init];
object2.intValue = 3;
object2.stringValue = @"Insert or replace objects";
[objects addObject:object2];
[database insertOrReplaceObjects:objects
into:tableName];
}
//Insert auto increment
{
WCTSampleConvenient *object = [[WCTSampleConvenient alloc] init];
object.isAutoIncrement = YES;
object.stringValue = @"Insert auto increment";
[database insertObject:object
into:tableName];
}删除
deleteAllObjectsFromTable:删除表内的所有数据deleteObjectsFromTable:后可组合接where、orderBy、limit、offset以删除部分数据
// DELETE FROM message WHERE localID>0;
BOOL result = [database deleteObjectsFromTable:@"message"
where:Message.localID > 0];
// DELETE FROM message WHERE localID>0 AND content IS NULL LIMIT 1;
BOOL result = [database deleteObjectsFromTable:@"message"
where:Message.localID>0 && Message.content != nil
limit:1];
//Delete
{
BOOL ret = [database deleteAllObjectsFromTable:tableName];
}
//Delete with condition/order/offset/limit
{
BOOL ret = [database deleteObjectsFromTable:tableName
where:WCTSampleConvenient.intValue.in({1, 2, 3})];
}
//Delete with condition/order/offset/limit
{
BOOL ret = [database deleteObjectsFromTable:tableName
where:WCTSampleConvenient.intValue.in(@[ @(1), @(2), @(3) ])];
}更新
updateAllRowsInTable:onProperties:withObject:，通过object更新数据库中所有指定列的数据updateRowsInTable:onProperties:withObject:后可组合接where、orderBy、limit、offset以通过object更新指定列的部分数据updateAllRowsInTable:onProperty:withObject:，通过object更新数据库某一列的数据updateRowsInTable:onProperty:withObject:后可组合接where、orderBy、limit、offset以通过object更新某一列的部分数据updateAllRowsInTable:onProperties:withRow:，通过数组更新数据库中的所有指定列的数据updateRowsInTable:onProperties:withRow:后可组合接where、orderBy、limit、offset以通过数组更新指定列的部分数据updateAllRowsInTable:onProperty:withRow:，通过数组更新数据库某一列的数据updateRowsInTable:onProperty:withRow:后可组合接where、orderBy、limit、offset以通过数组更新某一列的部分数
// UPDATE message SET content="Hello, Wechat!";
Message *message = [[Message alloc] init];
message.content = @"Hello, Wechat";
BOOL result = [database updateAllRowsInTable:@"message"
onProperties:Message.content
withObject:message];
// UPDATE message SET modifiedTime=? WHERE localID==1;
BOOL result = [database updateRowsInTable:@"message"
onProperty:Message.modifiedTime
withValue:[NSDate date]
where:Message.localID==1];
//Update by object
{
WCTSampleConvenient *object = [[WCTSampleConvenient alloc] init];
object.stringValue = @"Update by object";
[database updateAllRowsInTable:tableName
onProperties:WCTSampleConvenient.stringValue
withObject:object];
}
//Update by value
{
NSArray *row = [NSArray arrayWithObject:@"Update by value"];
[database updateAllRowsInTable:tableName
onProperties:WCTSampleConvenient.stringValue
withRow:row];
}
//Update with condition/order/offset/limit
{
WCTSampleConvenient *object = [[WCTSampleConvenient alloc] init];
object.stringValue = @"Update with condition/order/offset/limit";
[database updateRowsInTable:tableName
onProperties:WCTSampleConvenient.stringValue
withObject:object
where:WCTSampleConvenient.intValue > 0];
}查询
getOneObjectOfClass:fromTable:后可接where、orderBy、limit、offset以从数据库中取出一行数据并组合成objectgetOneObjectOnResults:fromTable:后可接where、orderBy、limit、offset以从数据库中取出一行数据的部分列并组合成objectgetOneRowOnResults:fromTable:后可接where、orderBy、limit、offset以从数据库中取出一行数据的部分列并组合成数组getOneColumnOnResult:fromTable:后可接where、orderBy、limit、offset以从数据库中取出一列数据并组合成数组getOneDistinctColumnOnResult:fromTable:后可接where、orderBy、limit、offset以从数据库中取出一列数据，并取 distinct 后组合成数组。getOneValueOnResult:fromTable:后可接where、orderBy、limit、offset以从数据库中取出一行数据的某一列getAllObjectsOfClass:fromTable:，取出所有数据，并组合成objectgetObjectsOfClass:fromTable:后可接where、orderBy、limit、offset以从数据库中取出一部分数据，并组合成objectgetAllObjectsOnResults:fromTable:，取出所有数据的指定列，并组合成objectgetObjectsOnResults:fromTable:后可接where、orderBy、limit、offset以从数据库中取出一部分数据的指定列，并组合成objectgetAllRowsOnResults:fromTable:，取出所有数据的指定列，并组合成数组getRowsOnResults:fromTable:后可接where、orderBy、limit、offset以从数据库中取出一部分数据的指定列，并组合成数组
// MARK: 查询
// SELECT * FROM message;
NSArray<Message *> *messages = [database getAllObjectsOfClass:Message.class
fromTable:@"message"];
// MARK: 查询并排序
// SELECT * FROM message ORDER BY localID;
NSArray<Message *> *messages2 = [database getObjectsOfClass:Message.class
fromTable:@"message"
orderBy:Message.localID.order()];
//Select One Object
{
WCTSampleConvenient *object = [database getOneObjectOfClass:WCTSampleConvenient.class
fromTable:tableName];
}
//Select Objects
{
NSArray<WCTSampleConvenient *> *objects = [database getAllObjectsOfClass:WCTSampleConvenient.class
fromTable:tableName];
}
//Select Objects with condition/order/offset/limit
{
NSArray<WCTSampleConvenient *> *objects = [database getObjectsOfClass:WCTSampleConvenient.class
fromTable:tableName
orderBy:WCTSampleConvenient.intValue.order(WCTOrderedAscending)
limit:1
offset:2];
}
//Select Part of Objects
{
NSArray<WCTSampleConvenient *> *objects =
[database getAllObjectsOnResults:WCTSampleConvenient.stringValue
fromTable:tableName];
}
//Select column
{
WCTOneColumn *objects = [database getOneColumnOnResult:WCTSampleConvenient.stringValue
fromTable:tableName];
for (NSString *string : objects) {
//do sth
}
}
//Select row
{
WCTOneRow *row = [database getOneRowOnResults:{
WCTSampleConvenient.intValue,
WCTSampleConvenient.stringValue}
fromTable:tableName];
NSNumber *intValue = (NSNumber *) row[0];
NSString *stringValue = (NSString *) row[1];
}
//Select one value
{
NSNumber *count = [database getOneValueOnResult:WCTSampleConvenient.AnyProperty.count()
fromTable:tableName];
}
//Select aggregation 聚合查询
{
WCTOneRow *row = [database getOneRowOnResults:{
WCTSampleConvenient.intValue.avg(),
WCTSampleConvenient.stringValue.count(),
}
fromTable:tableName];
}
//Select distinct aggregation
//取出所有数据的指定列，并组合成 object
{
NSArray *objects = [database getAllObjectsOnResults:WCTSampleConvenient.stringValue.count(true)
fromTable:tableName];
}
//Select distinct result
//从数据库中取出一列数据，并取 distinct 去重后组合成数组
{
NSNumber *distinctCount = [database getOneDistinctValueOnResult:WCTSampleConvenient.intValue fromTable:tableName];
}WCTTable
// WCTTable 相当于预设了表名和类名的 WCTDatabase 对象，接口和 WCTDatabase 基本一致
WCTTable *table = [database getTableOfName:@"message" withClass:Message.class];
// MARK: 通过 WCTTable 查询
// SELECT * FROM message ORDER BY localID;
NSArray<Message *> *queryResult = [table getObjectsOrderBy:Message.localID.order()];事务（Transaction）
1. 通过 runTransaction 接口执行事务
BOOL commited = [database runTransaction:^BOOL{
[database insertObject:message into:@"message"];
return YES; // 返回 YES 以 commit 事务，返回 NO 以 rollback 事务。
}];这种方式要求数据库操作在一个 Block 块内完成，简单易用。
2. 获取 WCTTransaction 对象执行事务
WCTTransaction *transaction = [database getTransaction];
BOOL result = [transaction begin];
[transaction insertObject:message into:@"message"];
result = [transaction commit];
if (!result) {
// 如果事务执行失败，则执行 rollback 回滚
[transaction rollback];
NSLog(@"%@",transaction.error);
}WINQ（WCDB 语言集成查询）
WINQ 将自然查询的 SQL 语言集成到了 C++ 中，可以通过类似函数调用的方式来写 SQL 查询。
WINQ 接口语法：
- 一元操作符：+、-、! 等
- 二元操作符：||、&&、+、-、*、/、|、&、<<、>>、<、<=、==、!=、>、>= 等
- 范围比较：IN、BETWEEN 等
- 字符串匹配：LIKE、GLOB、MATCH、REGEXP 等
- 聚合函数：AVG、COUNT、MAX、MIN、SUM 等
- ...
以下是 SQL 和 WINQ 之间转换的一些例子：
| 类型 | SQL 示例 | WINQ 示例 |
|---|---|---|
| 排序 | ORDER BY localID ASC |
Message.localID.order(WCTOrderedAscending) |
| 多字段排序 | ORDER BY localID ASC, content DESC |
{Message.localID.order(WCTOrderedAscending), Message.content.order(WCTOrderedDescending)} |
| 聚合函数 | MAX(localID) |
Message.localID.max() |
| 条件语句 | localID == 2 AND content IS NOT NULL |
Message.localID == 2 && Message.content.isNotNull() |
| 多个字段组合 | localID, content |
{Message.localID, Message.content} |
| * | COUNT(*) |
Message.AnyProperty.count() |
| 所有 ORM 定义的字段 | localID, content, createTime, modifiedTime |
Message.AllProperties |
| 指定 table | myTable.localID |
Message.localID.inTable("myTable") |
注：Max() 函数返回一列中的最大值。
字段映射与运算符
通过 className.propertyName 的方式，获得数据库内字段的映射，以此书写 SQL 的条件、排序、过滤等等所有语句。
/**
SELECT MAX(createTime), MIN(createTime)
FROM message
WHERE localID>0 AND content IS NOT NULL
*/
[database getObjectsOnResults:{Message.createTime.max(), Message.createTime.min()}
fromTable:@"message"
where:Message.localID > 0 && Message.content.isNotNull()];
/**
SELECT DISTINCT localID
FROM message
ORDER BY modifiedTime ASC
LIMIT 10
*/
[database getObjectsOnResults:Message.localID.distinct()
fromTable:@"message"
orderBy:Message.modifiedTime.order(WCTOrderedAscending)
limit:10];
/**
DELETE FROM message
WHERE localID BETWEEN 10 AND 20 OR content LIKE 'Hello%'
*/
[database deleteObjectsFromTable:@"message"
where:Message.localID.between(10, 20) || Message.content.like("Hello%")];字段组合
多个字段映射可以通过大括号 {} 进行组合。
/**
SELECT localID, content FROM message;
*/
[database getAllObjectsOnResults:{Message.localID, Message.content}
fromTable:@"message"];
/**
SELECT localID, createTime
FROM message
WHERE localID>=1 OR modified!=createTime;
*/
[database getObjectsOnResults:{Message.localID, Message.createTime}
fromTable:@"message"
where:Message.localID>=1||Message.modifiedTime!=Message.createTime];
/**
SELECT *
FROM message
ORDER BY createTime ASC, localID DESC;
*/
[database getObjectsOfClass:Message.class
fromTable:@"message"
orderBy:{Message.createTime.order(WCTOrderedAscending), Message.localID.order(WCTOrderedDescending)}];
AllProperties
className.AllProperties 用于获取类定义的所有字段映射的列表。
/**
SELECT localID, content, createTime, modifiedTime FROM message;
*/
[database getAllObjectsOnResults:Message.AllProperties
fromTable:@"message"];
AnyProperty
className.AnyProperty 用于指代 SQL 中的 *。
/**
SELECT count(*) FROM message;
*/
NSNumber *count = [database getOneValueOnResult:Message.AnyProperty.count()
fromTable:@"message"];链式接口
链式调用是指对象的接口返回一个对象，从而允许在单个语句中将调用链接在一起，而不需要变量来存储中间结果。
WCDB 对于增删改查操作，都提供了对应的类以实现链式调用
WCTInsertWCTDeleteWCTUpdateWCTSelectWCTRowSelectWCTMultiSelect
WCTSelect *select = [database prepareSelectObjectsOnResults:Message.localID.max()
fromTable:@"message"];
NSArray<Message *> *objects= [[[[select where:Message.localID > 0]
groupBy:{Message.content}]
orderBy:Message.createTime.order()]
limit:10].allObjects;as 重定向
基于 ORM 的支持，我们可以从数据库直接取出一个 Object。然而，有时候需要取出并非是某个字段，而是有一些组合。
从数据库中取出了消息的最新的修改时间，并以此将此时间作为消息的创建时间，新建了一个 message。
NSNumber *maxModifiedTime = [database getOneValueOnResult:Message.modifiedTime.max()
fromTable:@"message"];
Message *lastMessage = [[Message alloc] init];
lastMessage.createTime = [NSDate dateWithTimeIntervalSince1970:maxModifiedTime.doubleValue];as 重定向，它可以将一个查询结果重定向到某一个字段，如下：
// as(Message.createTime) 语法，将查询结果重新指向 createTime
Message *lastMessage = [database getOneObjectOnResults:Message.modifiedTime.max().as(Message.createTime)
fromTable:@"message"];多表查询
通过 WCTMultiSelect 的链式接口，可以同时从表中取出多个类的对象。
/*
SELECT contact.nickname, contact_ext.headImg
FROM contact, contact_ext
WHERE contact.name==contact_ext.name
*/
WCTMultiSelect *multiSelect = [[database prepareSelectMultiObjectsOnResults:{
Contact.nickname.inTable(@"contact"),
ContactExt.nickname.inTable(@"contact_ext")
} fromTables:@[ @"contact", @"contact_ext" ]] where:Contact.name.inTable(@"contact") == ContactExt.name.inTable(@"contact_ext")];
while ((multiObject = [multiSelect nextMultiObject])) {
Contact *contact = (Contact *) [multiObject objectForKey:@"contact"];
ContactExt *contactExt = (ContactExt *) [multiObject objectForKey:@"contact_ext"];
//...
}加密
WCDB 提供基于 SQLCipher 的数据库加密功能，如下：
WCTDatabase *database = [[WCTDatabase alloc] initWithPath:path];
NSData *password = [@"MyPassword" dataUsingEncoding:NSASCIIStringEncoding];
[database setCipherKey:password];全局监控
WCDB 内提供统计的接口注册获取数据库操作的 SQL、性能、错误等，开发者可以将这些信息打印到日志或上报到后台，以调试或统计。
//Error Monitor
[WCTStatistics SetGlobalErrorReport:^(WCTError *error) {
NSLog(@"[WCDB]%@", error);
}];
//Performance Monitor
[WCTStatistics SetGlobalPerformanceTrace:^(WCTTag tag, NSDictionary<NSString *, NSNumber *> *sqls, NSInteger cost) {
NSLog(@"Database with tag:%d", tag);
NSLog(@"Run :");
[sqls enumerateKeysAndObjectsUsingBlock:^(NSString *sqls, NSNumber *count, BOOL *) {
NSLog(@"SQL %@ %@ times", sqls, count);
}];
NSLog(@"Total cost %ld nanoseconds", (long)cost);
}];
//SQL Execution Monitor
[WCTStatistics SetGlobalSQLTrace:^(NSString *sql) {
NSLog(@"SQL: %@", sql);
}];参考
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