Simple use of SQLite

The results of the program run as follows:

Enter name and age, and click the "Confirm Insert" button to insert a record into the database.

The program code is as follows: (with detailed comments, I believe everyone can understand Kazakhstan!!!)

//
Viewcontroller.m
Basic operation of SQLite
//
Created by Mac1 on 15/10/6.
Copyright (c) 2015 www.iphonetrain.com. All rights reserved.
//

#import "ViewController.h"

Import library files
#import <sqlite3.h>

@interface Viewcontroller ()

Name
@property (Weak, nonatomic) Iboutlet Uitextfield *nametextfield;

Age
@property (Weak, nonatomic) Iboutlet Uitextfield *agetextfield;


@property (nonatomic,assign) sqlite3 *db; global variable defaults to NULL

"Confirm Insert" button
-(ibaction) insertaction;

@end

@implementation Viewcontroller

-(void) Viewdidload {
[Super Viewdidload];


The path to the build database
NSString *dbfilepath = [Nshomedirectory () stringbyappendingpathcomponent:@ "documents/test.db"];

Print Database save path
NSLog (@ "Dbfilepath =%@", Dbfilepath);


1. Create the database, and if there is no database, create

_db = NULL;

int status = Sqlite3_open (dbfilepath.utf8string, &_db);
if (status = = Sqlite_ok) {
NSLog (@ "Open database successfully!");


2. Create a table
char *errmsg = NULL;
Sqlite3_exec (_db, "CREATE TABLE IF not EXISTS t_user (ID integer PRIMARY KEY, Name text, age integer)", NULL, NULL, &AMP;E RRMSG);
if (errmsg) {
NSLog (@ "Failed to create TABLE!");

}

}
Querying data
[Self querydata];

}

"Confirm Insert" button is clicked

-(ibaction) insertaction {

DML Insert

NSString *insertsql = [NSString stringwithformat:@ "INSERT into T_user (name,age) VALUES ('%@ ', '%ld ') ', _ Nametextfield.text,[_agetextfield.text IntegerValue]];

Inserting data

char *error = NULL;
Sqlite3_exec (_db, insertsql.utf8string, NULL, NULL, &AMP;ERROR);

if (Error) {

NSLog (@ "Insert record failed!");

}
}


DQL use of query statements

-(void) querydata{

Prepare the query (check the legality of the SQL statement)

Parameter value-1 indicates the internal calculation size of the program
sqlite3_stmt *stmt = NULL;

int status = SQLITE3_PREPARE_V2 (_db, "select * from T_user",-1, &stmt, NULL);

Indicates that there is data
if (status = = Sqlite_ok) {

Sqlite3_step (stmt) = = Sqlite_row The data that the current stmt points to has a value
while (Sqlite3_step (stmt) = = Sqlite_row) {

Take out the value in the Name field in one piece of data

Const unsigned char *name = Sqlite3_column_text (stmt, 1);

Take out the value in the age field in one piece of data
int age = Sqlite3_column_int (stmt, 2);

NSLog (@ "name =%s, age =%d", name,age);

}

}
}
@end

However, the operation of the database, generally using the third-party framework FMDB operation

: Https://github.com/ccgus/fmdb

Simple use of SQLite