數據庫增刪改查的基本sql語法略........ 直接進入SQLite3的使用。
SQLite3常用函數:
1、打開數據庫連接
int sqlite3_open(
const char *filename, /* 數據庫文件名(UTF-8)*/
sqlite3 **ppDb /* OUT: SQLite 數據庫句柄 */
);
2、關閉數據庫
int sqlite3_close(sqlite3*); //參數數據庫句柄。
3、sqlite3_exec()可以執行任何SQL語句,比如創表、更新、插入和刪除操作。但是一般不用它執行查詢語句,因爲它不會返回查詢到的數據
int sqlite3_exec(
sqlite3*, /* 已經打開的數據庫句柄 */
const char *sql, /* 要執行的Sql語句 可以包括事務("BEGIN TRANSACTION")、回滾("ROLLBACK")和提交("COMMIT")*/
sqlite_callback, /* 回調函數*/
void *, /*傳遞給回調函數的參數*/
char **errmsg /* 保存錯誤信息*/
);
4、sql語句準備函數
int sqlite3_prepare_v2(
sqlite3 *db, /* 已經打開的數據庫句柄 */
const char *zSql, /*
要執行的Sql語句 , UTF-8 encoded */
int nByte, /* 如果nByte小於0,則函數取出zSql中從開始到第一個0終止符的內容;如果nByte不是負的,那麼它就是這個函數能從zSql中讀取的字節數的最大值。如果nBytes非負,zSql在第一次遇見’/000/或’u000’的時候終止 */
sqlite3_stmt **ppStmt, /*上面提到zSql在遇見終止符或者是達到設定的nByte之後結束,假如zSql還有剩餘的內容,那麼這些剩餘的內容被存放到pZTail中,不包括終止符*/
const char **pzTail /* 能夠使用sqlite3_step()執行的編譯好的準備語句的指針,如果錯誤發生,它被置爲NULL,如假如輸入的文本不包括sql語句。調用過程必須負責在編譯好的sql語句完成使用後使用sqlite3_finalize()刪除它 */
);
5、sqlite3_bind_text(
sqlite3_stmt*, /* 已經打開的數據庫句柄 */
int, /* 佔位符的位置,第一個佔位符的位置是1,不是0 */
const char*, /* 佔位符要綁定的值 */
int, /* 指在第3個參數中所傳遞數據的長度,對於C字符串,可以傳遞-1代替字符串的長 */
void(*)(void*) /* 可選的函數回調,一般用於在語句執行後完成內存清理工作*/
);
6、sqlite_step():執行SQL語句,返回SQLITE_DONE代表成功執行完畢
8、sqlite_finalize():銷燬sqlite3_stmt *對象
9、int sqlite3_get_table執行Sql查詢,執行一次查詢Sql 並且返回得到一個記錄集。
int sqlite3_get_table(
sqlite3*, /* 已經打開的數據庫句柄 */
const char *sql, /* 要執行的Sql語句*/
char ***resultp, /* 保存返回記錄集的指針,包含列名及烈屬性值。行優先,從0起計數下標*/
int *nrow, /*返回記錄行數數*/
int *ncolumn, /* 返回記錄列數*/
char **errmsg /* 返回錯誤信息*/
)
10、void sqlite3_free_table(char **result); 釋放當前查詢的記錄集所佔用的內存
佔位插入例子:
char *sql = "insert into t_person(name, age) values(?, ?);";
sqlite3_stmt *stmt;
if (sqlite3_prepare_v2(db, sql, -1, &stmt, NULL) == SQLITE_OK) {
sqlite3_bind_text(stmt, 1, "小明", -1, NULL);
sqlite3_bind_int(stmt, 2, 27);
}
if (sqlite3_step(stmt) != SQLITE_DONE) {
NSLog(@"插入數據錯誤");
}
sqlite3_finalize(stmt);
查詢例子:
const char *sql = "select name,price from t_shop";
sqlite3_stmt *stmt = NULL;
int status = sqlite3_prepare_v2(self.db, sql , -1, &stmt, NULL);
if (status == SQLITE_OK) { // 準備成功 -- SQL語句正確
while (sqlite3_step(stmt) == SQLITE_ROW) {// 成功取出一條數據
const char *name = (const char *)sqlite3_column_text(stmt, 0);
const char *price = (const char *)sqlite3_column_text(stmt, 1);
NSString name = [NSString stringWithUTF8String:name];
NSString price = [NSString stringWithUTF8String:price];
}
}
2.實戰案例:輸入商品、價格,添加插入一條記錄顯示在table中,也可以查詢。
1.項目引入libsqlite3
2.代碼:
//
// ViewController.m
// sqlite
//
//
#import "ViewController.h"
#import <sqlite3.h>
#import "ZXHShop.h"
@interface ViewController ()<UITableViewDataSource,UISearchBarDelegate>
@property (weak, nonatomic) IBOutlet UITextField *nameField;
@property (weak, nonatomic) IBOutlet UITextField *priceFIeld;
@property (assign,nonatomic) sqlite3 *db;
@property (weak, nonatomic) IBOutlet UITableView *tableVIew;
@property (strong,nonatomic) NSMutableArray *shops;
- (IBAction)insertShop;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
//初始化數據庫
[self setupDB];
[self setupData];
// 增加搜索框
UISearchBar *searchBar = [[UISearchBar alloc] init];
searchBar.frame = CGRectMake(0, 0, 320, 44);
searchBar.delegate = self;
self.tableVIew.tableHeaderView = searchBar;
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(NSMutableArray *)shops{
if (!_shops) {
_shops = [[NSMutableArray alloc] init];
}
return _shops;
}
//初始化數據庫
-(void)setupDB{
//沙盒路徑
NSString *filename = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject] stringByAppendingPathComponent:@"shops.sqlite"];
NSLog(@"%@",filename);
// 如果數據庫文件不存在, 系統會自動創建文件自動初始化數據
// sqlite3_open([path UTF8String], &db); 參入:一:存放地址 二:數據庫實例
int status = sqlite3_open(filename.UTF8String, &_db); //返回SQLITE_OK代碼打開成功
if (status == SQLITE_OK) {//打開成功
//創建表
const char *sql= "create table if not exists t_shop(id integer primary key,name text not null,price real)";
char *errmsg = NULL;
sqlite3_exec(self.db, sql, NULL, NULL, &errmsg);
if (errmsg) {
NSLog(@"創建表失敗!%s",errmsg);
}
}else{
NSLog(@"打開數據庫失敗!");
}
}
//新增商品
- (IBAction)insertShop {
NSString *sql = [NSString stringWithFormat:@"insert into t_shop(name,price) values('%@',%f)",self.nameField.text,self.priceFIeld.text.doubleValue];
char *errmsg = NULL;
sqlite3_exec(self.db, sql.UTF8String, NULL, NULL, &errmsg);
if (errmsg) {
NSLog(@"添加商品失敗!");
}else{
[self alert];
ZXHShop *shop = [[ZXHShop alloc] init];
shop.name = self.nameField.text;
shop.price = self.priceFIeld.text;
[self.shops addObject:shop];
self.nameField.text = @"";
self.priceFIeld.text = @"";
[self.tableVIew reloadData];
}
}
/**
查詢數據
*/
-(void)setupData{
const char *sql = "select name,price from t_shop";
sqlite3_stmt *stmt = NULL;
int status = sqlite3_prepare_v2(self.db, sql , -1, &stmt, NULL);
if (status == SQLITE_OK) { // 準備成功 -- SQL語句正確
while (sqlite3_step(stmt) == SQLITE_ROW) {// 成功取出一條數據
const char *name = (const char *)sqlite3_column_text(stmt, 0);
const char *price = (const char *)sqlite3_column_text(stmt, 1);
ZXHShop *shop = [[ZXHShop alloc] init];
shop.name = [NSString stringWithUTF8String:name];
shop.price = [NSString stringWithUTF8String:price];
[self.shops addObject:shop];
}
}
}
-(void)alert{
UIAlertController *alert = [UIAlertController alertControllerWithTitle:NULL message:@"新增成功" preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *close = [UIAlertAction actionWithTitle:@"關閉" style:UIAlertActionStyleCancel handler:nil];
[alert addAction:close];
[self presentViewController:alert animated:YES completion:nil];
}
#pragma mark table數據源方法
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return self.shops.count;
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
static NSString *ID = @"shop";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:ID];
if (!cell) {
cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:ID];
cell.backgroundColor = [UIColor grayColor];
}
ZXHShop *shop = self.shops[indexPath.row];
cell.textLabel.text = shop.name;
cell.detailTextLabel.text = shop.price;
cell.detailTextLabel.textColor = [UIColor redColor];
return cell;
}
#pragma mark searchBarDelegate
-(void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText{
[self.shops removeAllObjects];
NSString *sql = [NSString stringWithFormat:@"select name,price from t_shop where name like '%%%@%%' or price like '%%%@%%'",searchText,searchText];
sqlite3_stmt *stmt = NULL;
int status = sqlite3_prepare_v2(self.db, sql.UTF8String, -1, &stmt, NULL);
if (status == SQLITE_OK) {
while (sqlite3_step(stmt) == SQLITE_ROW) {
const char *name = (const char *)sqlite3_column_text(stmt, 0);
const char *price = (const char *)sqlite3_column_text(stmt, 1);
ZXHShop *shop = [[ZXHShop alloc]init];
shop.name = [NSString stringWithUTF8String:name];
shop.price = [NSString stringWithUTF8String:price];
[self.shops addObject:shop];
}
}
[self.tableVIew reloadData];
}
@end
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);