ios对SQLite3的使用

​​ios对SQLite3的使用​​

一、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 <UIKit/UIKit.h>

#import "sqlite3.h"

@interface HomeViewController : UIViewController{

    sqlite3 *db; //声明一个sqlite3数据库

}

- (NSString *)filePath;//数据库文件的路径。一般在沙箱的Documents里边操作

@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：

sqlite3数据库打开时的返回值及其所代表的含义

致力于ios开发