sqlite3 常用语法 增删改查

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创建表名 t_student 主键为 id

CREATE TABLE t_student (id integer PRIMARY KEY, name text,age integer,score real);

如果不存在就创建

CREATE TABLE IF NOT EXISTS t_student (id integer PRIMARY KEY, name text,age integer,score real);

主键自动长

CREATE TABLE IF NOT EXISTS t_student (id integer PRIMARY KEY AUTOINCREMENT, name text,age integer,score real);

增加数据
INSERT INTO t_student (name,age,score) VALUES ('jams',10,10);

更新 全部设了99
UPDATE t_student SET score = 99;
删除内容 某
DELETE FROM t_student WHERE id = 2;
删除内容表内全部
DELETE FROM t_student;
删除整表
DROP TABLE t_student;

查找
SELECT * FROM t_student WHERE age > 50;
查找 总数
SELECT count(name) FROM t_student WHERE age > 50;

模糊查询 %5%
SELECT name , phone FROM t_student WHERE phone LIKE '%%%@%%'
/别名/
SELECT name as myName, age as myAge, score as myScore FROM t_student;
SELECT name myName, age myAge, score myScore FROM t_student;
SELECT s.name myName, s.age myAge, s.score myScore FROM t_student s WHERE s.age > 50;

/排序/
SELECT * FROM t_student WHERE score > 50 ORDER BY age DESC;
SELECT * FROM t_student WHERE score < 50 ORDER BY age ASC , score DESC;

/分页/ 从第几个后 开始 取多少个 0 5 5 5 10 5
SELECT * FROM t_student ORDER BY id ASC LIMIT 30, 10;

/简单约束/ 主键PRIMARY KEY 自动增长AUTOINCREMENT
不会空 NOT NULL 默认DEFAULT 1
CREATE TABLE IF NOT EXISTS t_student(id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INTEGER);
CREATE TABLE IF NOT EXISTS t_student(id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, age INTEGER NOT NULL);
CREATE TABLE IF NOT EXISTS t_student(id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT UNIQUE, age INTEGER);
CREATE TABLE IF NOT EXISTS t_student(id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INTEGER DEFAULT 1);

------------------------oc创建数据库-------------------------------
添加动态库

import "ViewController.h"

import

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添加动态库

import "ViewController.h"

import

@interface ViewController ()
{
sqlite3 *_db;
}
@end

@implementation ViewController

• (void)viewDidLoad {
  [super viewDidLoad];
  //1. 创建了一个数据库的 文件

  //1> 数据库文件路径 2>数据库的句柄 3>

  NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];

  NSString *dbPath = [path stringByAppendingPathComponent:@"test.sqlite"];
  NSLog(@"%@",dbPath);
  //打开数据库文件 如果没有就创建一个
  int result = sqlite3_open(dbPath.UTF8String, &_db);

  if (result == SQLITE_OK) {
  NSLog(@"创建数据库成功!");

    //2. 创建表  指定字段
    NSString *sql = [NSString stringWithFormat:@"CREATE TABLE IF NOT EXISTS t_student (id INTEGER PRIMARY KEY AUTOINCREMENT , name TEXT , score REAL)"];
    char *eror = nil;
    int tableOk =  sqlite3_exec(_db, sql.UTF8String, NULL, NULL,&eror);
    
    if (tableOk == SQLITE_OK) {
        NSLog(@"创建表成功!");
    }else{
        NSLog(@"创建表失败!");
    }
    
    
    //3. 填充数据
    //crud
    
}else{
    NSLog(@"创建数据库失败!");
}

}

• (IBAction)adddb {

    //2. 增加  数据  100条
  

  for (int i = 0; i < 100; i++) {
  NSString *sql = [NSString stringWithFormat:@"INSERT INTO t_student (name , score) VALUES('JACK-%d',%f)",i,arc4random_uniform(1000)/10.0];
  char *eror = nil;
  int tableOk = sqlite3_exec(_db, sql.UTF8String, NULL, NULL,&eror);

    if (tableOk == SQLITE_OK) {
        NSLog(@"添加数据成功!");
    }else{
        NSLog(@"添加数据失败!");
    }
  

  }

}

• (IBAction)deletedb {

  NSString *sql = [NSString stringWithFormat:@"DELETE FROM t_student WHERE score < 20"];
  char *eror = nil;
  int tableOk = sqlite3_exec(_db, sql.UTF8String, NULL, NULL,&eror);

  if (tableOk == SQLITE_OK) {
  NSLog(@"删除数据成功!");
  }else{
  NSLog(@"删除数据失败!");
  }
  }

• (IBAction)updatedb {

  NSString *sql = [NSString stringWithFormat:@"UPDATE t_student SET name = 'kobe' WHERE id < 50"];
  char *eror = nil;
  int tableOk = sqlite3_exec(_db, sql.UTF8String, NULL, NULL,&eror);

  if (tableOk == SQLITE_OK) {
  NSLog(@"更新数据成功!");
  }else{
  NSLog(@"更新数据失败!");
  }

}

• (IBAction)selectdb {

//参数1> 数据库的指针  2>sql语句 3> 负责接收处理结果
sqlite3_stmt *stmt = nil;

NSString *sql = [NSString stringWithFormat:@"SELECT  id,name , score FROM t_student WHERE score > 60"];
int result =  sqlite3_prepare_v2(_db, sql.UTF8String, -1, &stmt, NULL);

if (result == SQLITE_OK) {
   
    while(sqlite3_step(stmt) == SQLITE_ROW){
        
      int s_id =   sqlite3_column_int(stmt,0);
      unsigned char *name =  (unsigned char *) sqlite3_column_text(stmt,1);
      double score =   sqlite3_column_double(stmt,2);
    
    
  NSLog(@"%d  - %@ - %f",s_id,[NSString stringWithUTF8String:(const char *)name],score);
        
    }
}

}

@end