1创建一个model类,
.h文件
#import <Foundation/Foundation.h>@interface IWStudent : NSObject
@property (nonatomic, assign) int ID;
@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) int age;
@end.m文件
#import "IWStudent.h"@implementation IWStudent@end2创建工具类....封装方法
.h文件
#import <Foundation/Foundation.h>
@class IWStudent;@interface IWStudentTool : NSObject/***  添加学生**  @param student 需要添加的学生*/
+ (BOOL)addStudent:(IWStudent *)student;/***  获得所有的学生**  @return 数组中装着都是IWStudent模型*/
+ (NSArray *)students;/***  根据搜索条件获得对应的学生**  @param condition 搜索条件*/
+ (NSArray *)studentsWithCondition:(NSString *)condition;@end.m文件
#import "IWStudentTool.h"
#import "IWStudent.h"
#import <sqlite3.h>@implementation IWStudentTool// static的作用：能保证_db这个变量只被IWStudentTool.m直接访问
static sqlite3 *_db;+ (void)initialize
{// 0.获得沙盒中的数据库文件名NSString *filename = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"student.sqlite"];// 1.创建(打开)数据库（如果数据库文件不存在，会自动创建）int result = sqlite3_open(filename.UTF8String, &_db);if (result == SQLITE_OK) {NSLog(@"成功打开数据库");// 2.创表const char *sql = "create table if not exists t_student (id integer primary key autoincrement, name text, age integer);";char *errorMesg = NULL;int result = sqlite3_exec(_db, sql, NULL, NULL, &errorMesg);if (result == SQLITE_OK) {NSLog(@"成功创建t_student表");} else {NSLog(@"创建t_student表失败:%s", errorMesg);}} else {NSLog(@"打开数据库失败");}
}+ (BOOL)addStudent:(IWStudent *)student
{NSString *sql = [NSString stringWithFormat:@"insert into t_student (name, age) values('%@', %d);", student.name, student.age];char *errorMesg = NULL;int result = sqlite3_exec(_db, sql.UTF8String, NULL, NULL, &errorMesg);return result == SQLITE_OK;
}+ (NSArray *)students
{// 0.定义数组NSMutableArray *students = nil;// 1.定义sql语句const char *sql = "select id, name, age from t_student;";// 2.定义一个stmt存放结果集sqlite3_stmt *stmt = NULL;// 3.检测SQL语句的合法性int result = sqlite3_prepare_v2(_db, sql, -1, &stmt, NULL);if (result == SQLITE_OK) {NSLog(@"查询语句是合法的");students = [NSMutableArray array];// 4.执行SQL语句，从结果集中取出数据while (sqlite3_step(stmt) == SQLITE_ROW) { // 真的查询到一行数据// 获得这行对应的数据
            IWStudent *student = [[IWStudent alloc] init];// 获得第0列的idstudent.ID = sqlite3_column_int(stmt, 0);// 获得第1列的nameconst unsigned char *sname = sqlite3_column_text(stmt, 1);student.name = [NSString stringWithUTF8String:(const char *)sname];// 获得第2列的agestudent.age = sqlite3_column_int(stmt, 2);// 添加到数组
            [students addObject:student];}} else {NSLog(@"查询语句非合法");}return students;
}+ (NSArray *)studentsWithCondition:(NSString *)condition
{// 0.定义数组NSMutableArray *students = nil;// 1.定义sql语句const char *sql = "select id, name, age from t_student where name like ?;";// 2.定义一个stmt存放结果集sqlite3_stmt *stmt = NULL;// 3.检测SQL语句的合法性int result = sqlite3_prepare_v2(_db, sql, -1, &stmt, NULL);if (result == SQLITE_OK) {NSLog(@"查询语句是合法的");students = [NSMutableArray array];// 填补占位符的内容NSString *newCondition = [NSString stringWithFormat:@"%%%@%%", condition];
//        NSLog(@"%@", newCondition);sqlite3_bind_text(stmt, 1, newCondition.UTF8String, -1, NULL);// 4.执行SQL语句，从结果集中取出数据while (sqlite3_step(stmt) == SQLITE_ROW) { // 真的查询到一行数据// 获得这行对应的数据
            IWStudent *student = [[IWStudent alloc] init];// 获得第0列的idstudent.ID = sqlite3_column_int(stmt, 0);// 获得第1列的nameconst unsigned char *sname = sqlite3_column_text(stmt, 1);student.name = [NSString stringWithUTF8String:(const char *)sname];// 获得第2列的agestudent.age = sqlite3_column_int(stmt, 2);// 添加到数组
            [students addObject:student];}} else {NSLog(@"查询语句非合法");}return students;
}
@end