Basic operations for adding, deleting, modifying, and querying the FMDN database of the iOS Database

Basic operations for adding, deleting, modifying, and querying the FMDN database of the iOS Database

FMDB (https://github.com/ccgus/fmdb) is not much to say first to add this library, in will be added, OK preparation work ready code.

# Import "DDViewController. h"

# Import "FMDB. h"

@ Interface DDViewController ()

{

FMDatabase * db;

}

@ End

@ Implementation DDViewController

/**

* First, you must have a location to store the Document path of the database under ios. Document is a folder that can be read and written in ios and you must create a database list.

*/

-(Void) viewDidLoad

{

[SuperviewDidLoad];

// Db = [FMDatabase new];

NSArray * paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES );

NSString * documentDirectory = [paths objectAtIndex: 0];

// DbPath: Specifies the database path in Document.

NSString * dbPath = [documentDirectory stringByAppendingPathComponent: @ "Test. db"];

// Create a database instance db. If the "Test. db" file does not exist in the path, sqlite automatically creates "Test. db"

Db = [FMDatabasedatabaseWithPath: dbPath];

If (! [Db open]) {

NSLog (@ "cocould not open db .");

Return;

}

// Set cache for the database to improve query efficiency

[DbsetShouldCacheStatements: YES];

// 1. Create a table named "User"

[SelfcreatTable];

// 2. Add data to the table

[SelfinsertData: @ "Straw hat" age: 23];

// 3. view the result

[SelfResultSet];

}

// Create a table

-(Void) creatTable

{

// When creating a table, it is best to determine whether your previous work is well performed.

If (! Db ){

NSLog (@ "database does not exist ");

}

If (! [Db open]) {

[Dbopen];

}

// Determine whether the table named "User" exists. If no table is created

If (! [Db tableExists: @ "User"]) {

// Create a table named User with two fields: string-type Name and integer-type Age.

[DbexecuteUpdate: @ "create table User (Name text, Age integer)"];

// [Self insertData: @ "Straw hat" age: 24];

}

}

// Insert data

-(Void) insertData :( NSString *) name age :( int) age

{

// Insert data using the type text in OC corresponding to NSString integer corresponding to int integer

[DbexecuteUpdate: @ "insert into User (Name, Age) VALUES (?,?) ", Name, [NSNumbernumberWithInt: age];

}

// Query results

-(Void) ResultSet

{

// Return the first matching result in the database

NSString * aa = [dbstringForQuery: @ "SELECT Name FROM User WHERE Age =? ", @" 20 "];

NSLog (@ "aa is % @", aa );

FMResultSet * rs = [dbexecuteQuery: @ "SELECT * FROM User"];

// Rs = [db executeQuery: @ "SELECT * FROM User WHERE Age =? ", @" 23 "];

While ([rs next]) {

NSLog (@ "% @", [rsstringForColumn: @ "Name"], [rsstringForColumn: @ "Age"]);

}

[Rsclose];

}

// Modify Table content

-(Void) Modify

{

[DbexecuteUpdate: @ "UPDATE User SET Name =? WHERE Name =? ", @" Li Si ", @" Zhang San "];

}

-(Void) didReceiveMemoryWarning

{

[SuperdidReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@ End