The detailed use of sqlite in iOS

This article shares the specific operation method of sqlite in ios for your reference. The specific content is as follows

#import <sqlite3.h>

@interface ViewController ()
{
 sqlite3 *_sqldb;
}

@end

@implementation ViewController

- (void)viewDidLoad
{
 [super viewDidLoad];
 // Do any additional setup after loading the view, typically from a nib.
 [self OpenDb];
 [self createTable];
 [self insertData];
 [self FindData];
}


// Open the database 

-(void)OpenDb{
 
 NSArray *arrs= NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
 // Create the database, open it directly if it exists, and open it if it doesn't 
 NSString *path=[arrs lastObject] ;
 NSString *documentpath= [path stringByAppendingPathComponent:@"sql.db"];
 int reslut= sqlite3_open([documentpath UTF8String], &_sqldb);
 if(reslut==SQLITE_OK){
 NSLog(@" The database has been opened ");
 }
 
}
// Create the table from the database instance 
-(void)createTable{
 // No parameters sql statements 
 const char* sql="create table if not exists t_person (id integer primary key autoincrement,name text,age integer);";
 char *error;
 //sqlite3_exec You can perform 1 Cut without parameters SQL Statements. If it is with parameters, it is best not to, prevent SQL Injection vulnerability attack 
 int resutl= sqlite3_exec(_sqldb, sql, NULL, NULL, &error);
 if(resutl==SQLITE_OK){
 NSLog(@" Table created successfully ");
 }
else{
 NSLog(@" Table creation failed -- %s",error);
}
}

// Insert data 
-(void)insertData{
 // With parameters SQL statements  "?" Is a placeholder with arguments 
 const char * sql="insert into t_person(name,age) values(?,?);";
 sqlite3_stmt *stmp;
 // In the implementation SQL Check before statement SQL Statement syntax ,-1 Represents the length of the string 
 int result= sqlite3_prepare_v2(_sqldb, sql, -1, &stmp, NULL);
 if(result==SQLITE_OK){
 NSLog(@" insert SQL Statement syntax is fine ");
 // Binding parameters , The index of the inserted parameter is from 1 start 
 sqlite3_bind_text(stmp, 1, "gcb", -1, NULL);
 sqlite3_bind_int(stmp, 2, 12);
 
 // Execute parameter SQL Statement, can't have exec
 int result=sqlite3_step(stmp);
 // Insert to determine , Want to use sqLite_Done To judge 
 if(result==SQLITE_DONE){
  NSLog(@" Insert the success ");
 }
 else{
  NSLog(@" Insert the failure ") ;
 }
 
 }
 else{
 NSLog(@" insert SQL Something is wrong with the statement ");
 }
}

-(void)FindData{
 char *sql="select id,name,age from t_person";
 // Query preparation step perform 
 sqlite3_stmt *stmt;
 // check SQL Syntax problems with statements 
 int result= sqlite3_prepare_v2(_sqldb, sql, -1, &stmt, NULL);
 if(result==SQLITE_OK){
 while (sqlite3_step(stmt)==SQLITE_ROW) {
  // The column of the query is 0 start   Insert columns from 1 start 
//  int xh = sqlite3_column_int(stmt, 0);
  int xh=sqlite3_column_int(stmt, 0);
  char * name=(char *)sqlite3_column_text(stmt, 1);
  int age=sqlite3_column_int(stmt, 2);
  NSLog(@"xh=%i-->name=%s-->age=%i",xh,name,age);
  
  
  
 }
 }
 else{
 NSLog(@" The query SQL Grammar is wrong ");
 }

}

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