SQLite3是一款开源的嵌入式关系型数据库，可移植性好、易使用、内存开销小
SQLite3是无类型的，意味着可以保存任何类型的数据到任意表的任意字段中。比如下列的创表语句是合法的： CREATE TABLE t_person(name, age); 为了保证可读性，建议还是把字段类型加上： CREATE TABLE t_person(name text, age integer); SQLite3常用的5种数据类型：text、integer、float、boolean、blob 在iOS中要使用SQLite3，需要添加库文件：libsqlite3.dylib并导入主头文件，这是一个C语言的库创建数据库（sqlite3_opendb）单步执行操作（sqlite3_exec）创建数据表数据操作插入数据更新数据删除数据查询操作sqlite3_prepare_v2检查sql的合法性sqlite3_step逐行获取查询结果sqlite3_coloum_xxx获取对应类型的内容sqlite3_finalize释放stmt
在Firefox中打开sqlite3（如果没有，选择工具->附加组件，添加即可）新建sqlite3数据库,Contacts,建立一个members表，字段 id,integer,主键，自增;name,varchar;email,varchar,null;birthday,datetime,null。向表中添加一些数据：
二、新建Empty Appliation，添加一个HomeViewController，和一个组件libsqlite3.dylib,来支持对sqlite3的连接，关闭，增删改查等操作。1. HomeViewController.h代码：#import#import "sqlite3.h"@interface HomeViewController : UIViewController{ //声明一个sqlite3数据库
sqlite3 *db;
}
//数据库文件的路径。一般在沙箱的Documents里边操作 - (NSString *)filePath;
@end 2. HomeViewController.m代码： #import "HomeViewController.h"@interface HomeViewController ()@end@implementation HomeViewController//该方法用于返回数据库在Documents文件夹中的全路径信息 - (NSString *)filePath{ NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDir = [paths objectAtIndex:0]; return [documentsDir stringByAppendingPathComponent:@"Contacts.sqlite"];}//打开数据库的方法 - (void)openDB{ if (sqlite3_open([[self filePath] UTF8String], &db) != SQLITE_OK) { sqlite3_close(db); NSAssert(0, @"数据库打开失败。"); }}//插入数据方法- (void)insertRecordIntoTableName:(NSString *)tableName withField1:(NSString *)field1 field1Value:(NSString *)field1Value andField2:(NSString *)field2 field2Value:(NSString *)field2Value andField3:(NSString *)field3 field3Value:(NSString *)field3Value{/*方法1：经典方法 NSString *sql = [NSString stringWithFormat:@"INSERT INTO '%@' ('%@', '%@', '%@') VALUES('%@', '%@', '%@')", tableName, field1, field2, field3, field1Value, field2Value, field3Value]; char *err; if (sqlite3_exec(db, [sql UTF8String], NULL, NULL, &err) != SQLITE_OK) { sqlite3_close(db); NSAssert(0, @"插入数据错误！"); } */ //方法2：变量的绑定方法 NSString *sql = [NSString stringWithFormat:@"INSERT INTO '%@' ('%@', '%@', '%@') VALUES (?, ?, ?)",tableName, field1, field2, field3]; sqlite3_stmt *statement; if (sqlite3_prepare_v2(db, [sql UTF8String], -1, &statement, nil) == SQLITE_OK) { sqlite3_bind_text(statement, 1, [field1Value UTF8String], -1,NULL); sqlite3_bind_text(statement, 2, [field2Value UTF8String], -1,NULL); sqlite3_bind_text(statement, 3, [field3Value UTF8String], -1,NULL); } if (sqlite3_step(statement) != SQLITE_DONE) { NSAssert(0, @"插入数据失败！"); sqlite3_finalize(statement); } } //查询数据- (void)getAllContacts{ NSString *sql = @"SELECT * FROM members"; sqlite3_stmt *statement; if (sqlite3_prepare_v2(db, [sql UTF8String], -1, &statement, nil) == SQLITE_OK) { while (sqlite3_step(statement) == SQLITE_ROW) { char *name = (char *)sqlite3_column_text(statement, 0); NSString *nameStr = [[NSString alloc] initWithUTF8String:name]; char *email = (char *)sqlite3_column_text(statement, 1); NSString *emailStr = [[NSString alloc] initWithUTF8String:email]; char *birthday = (char *)sqlite3_column_text(statement, 2); NSString *birthdayStr = [[NSString alloc] initWithUTF8String:birthday]; NSString *info = [[NSString alloc] initWithFormat:@"%@ - %@ - %@", nameStr, emailStr, birthdayStr]; NSLog(info); [nameStr release]; [emailStr release]; [birthdayStr release]; [info release]; } sqlite3_finalize(statement); }}- (void)viewDidLoad{ [self openDB]; [self insertRecordIntoTableName:@"members" withField1:@"name" field1Value:@"李1" andField2:@"email" field2Value:@"df@qq.com" andField3:@"birthday" field3Value:@"12-45-78"]; [self insertRecordIntoTableName:@"members" withField1:@"name" field1Value:@"李2" andField2:@"email" field2Value:@"df@qq.com" andField3:@"birthday" field3Value:@"12-45-78"]; [self insertRecordIntoTableName:@"members" withField1:@"name" field1Value:@"李3" andField2:@"email" field2Value:@"df@qq.com" andField3:@"birthday" field3Value:@"12-45-78"]; [self getAllContacts]; sqlite3_close(db); [super viewDidLoad];}@end插入数据后的效果： 查询的效果：
三、小结：
1.数据查询：sqlite3_exec()函数执行sql语句，在没有返回值的情况下（比如创建表格、插入记录、删除记录等操作中）很好用。
也会用到sqlite3_stat结构、sqlite3_prepare_v2()函数、sqlte3_step()函数和sqlite3_finalize()函数。
查询分三个阶段：准备阶段：sqlite3_stat、sqlite3_prepare_v2()
执行阶段：sqlte3_step()
终止阶段： sqlite3_finalize()
2.附表：