"iOS Development-105" SQLite third-party framework Fmdb, and using Fmdatabasequeue to ensure thread safety

(1): Https://github.com/ccgus/fmdb

(2) Attention points

--The statement can have a semicolon ";", or you can omit the semicolon.

--also need to add "libsqlite3.dylib" library to use.

--in the development of mobile, the database is not closed, that is, not how to use [self.db close], because each time the performance is re-opened, and each time the program shuts down, the database will naturally shut down at the same time.

(3) Usage

#import "ViewController.h" #import "FMDB.h" @interface Viewcontroller () @property (Nonatomic,strong) fmdatabase *db;-( ibaction) Insert: (ID) sender;-(ibaction) Delete: (ID) sender;-(ibaction) Update: (ID) sender;-(ibaction) Select: (ID)    sender; @end @implementation viewcontroller-(void) viewdidload {[Super viewdidload]; NSString *filepath=[[nssearchpathfordirectoriesindomains (NSDocumentDirectory, Nsuserdomainmask, YES) LastObject]    stringbyappendingpathcomponent:@ "Fmdb.sqlite"];    Create database Self.db=[fmdatabase Databasewithpath:filepath];        Open database if ([self.db Open]) {NSLog (@ "Open database succeeded");  To create a table, all operations except select are updated with BOOL createtableresult=[self.db executeupdate:@ "CREATE table IF not EXISTS t_student (ID        Integer PRIMARY KEY autoincrement,name text,age integer) "];        if (Createtableresult) {NSLog (@ "CREATE table succeeded");        }else{NSLog (@ "CREATE TABLE failed");    }}else{NSLog (@ "Failed to open database"); }}-(ibaction) Insert: (ID) sender {for (int index=0; Index<50;        index++) {nsstring *s_name=[nsstring stringwithformat:@ "andy%d", Arc4random ()%100];        NSNumber *[email protected] (arc4random ()%100);    [Self.db executeupdate:@ "INSERT into T_student (name,age) VALUES (?,?)", S_name,s_age]; }}-(ibaction) Delete: (ID) Sender {[self.db executeupdate:@ "Delete from t_student WHERE id=?", @1];} -(ibaction) Update: (ID) Sender {[self.db executeupdate:@ "Update t_student SET name= ' Jack ' WHERE id=?", @2];} -(Ibaction) Select: (ID) Sender {//Get result set, return parameter is query result fmresultset *rs=[self.db executequery:@ "select * from T_student W    Here Age>? ", @50];        while ([Rs next]) {int id=[rs intforcolumn:@ "ID"];        NSString *name=[rs stringforcolumn:@ "NAME"];        int Age=[rs intforcolumn:@ "age"];    NSLog (@ "%d%@%d", id,name,age); }} @end

(4) Use Fmdatabasequeue to ensure thread safety (it is recommended to do so later)

--The main thing is that when you create a database, the database is opened by default

--many subsequent operations, because of the need to operate in the database, it is necessary to use the queue's Indatabase method to bring up the database, execute the operation code in the block.

#import "ViewController.h" #import "FMDB.h" @interface Viewcontroller () @property (nonatomic,strong) Fmdatabasequeue * queue;-(ibaction) Insert: (ID) sender;-(ibaction) Delete: (ID) sender;-(ibaction) Update: (ID) sender;-(ibaction) Select    :(ID) sender; @end @implementation viewcontroller-(void) viewdidload {[Super viewdidload]; NSString *filepath=[[nssearchpathfordirectoriesindomains (NSDocumentDirectory, Nsuserdomainmask, YES) LastObject]    stringbyappendingpathcomponent:@ "Fmdb.sqlite"];    Create the database and join the queue, at this time the database has been opened by default, do not have to open manually, only need to remove the database from the queue self.queue=[fmdatabasequeue Databasequeuewithpath:filepath]; Take out the database, here DB is database, create table in database [Self.queue indatabase:^ (Fmdatabase *db) {//CREATE TABLE BOOL createtableresult=[db E        xecuteupdate:@ "CREATE TABLE IF not EXISTS t_student (ID integer PRIMARY KEY autoincrement,name text,age integer)"];        if (Createtableresult) {NSLog (@ "CREATE table succeeded");        }else{NSLog (@ "CREATE TABLE failed"); }    }];} -(ibaction) Insert: (ID) sender {[SELf.queue indatabase:^ (Fmdatabase *db) {for (int index=0; index<50; index++) {nsstring *s_name=[nsst            Ring stringwithformat:@ "andy%d", Arc4random ()%100];            NSNumber *[email protected] (arc4random ()%100);        [DB executeupdate:@ INSERT into T_student (name,age) VALUES (?,?) ", S_name,s_age]; }    }];} -(Ibaction) Delete: (ID) Sender {[Self.queue indatabase:^ (Fmdatabase *db) {[db executeupdate:@] Delete from T_stu    Dent where id=? ", @1]; }];} -(ibaction) Update: (ID) Sender {[Self.queue indatabase:^ (Fmdatabase *db) {[DB executeupdate:@] Update t_student    SET name= ' Jack ' WHERE id=? ", @2]; }];}  -(Ibaction) Select: (ID) Sender {[Self.queue indatabase:^ (Fmdatabase *db) {//Get result set, return parameter is query result Fmresultset        *rs=[db executequery:@ "SELECT * from T_student where age>?", @50];            while ([Rs next]) {int id=[rs intforcolumn:@ "ID"];            NSString *name=[rs stringforcolumn:@ "NAME"]; int Age=[rs intforcolumn:@ "Age"];        NSLog (@ "%d%@%d", id,name,age); }    }];}

(5) If you want to ensure that multiple operations succeed or fail at the same time, use a transaction, that is, to put multiple operations in the same transaction.

--fmdb, get the database direct operation transaction, as follows:

-(ibaction) Update: (ID) Sender {    [self.queue indatabase:^ (Fmdatabase *db) {        [db begintransaction];        [DB executeupdate:@ "UPDATE t_student SET name= ' Jack ' WHERE id=?", @2];        [DB executeupdate:@ "UPDATE t_student SET name= ' Tomy ' WHERE id=?", @3];        When the situation is not found, the active rollback is made with the following statement. Otherwise, according to the result of the commit, such as success success, if not successful rollback        [db rollback];        [DB executeupdate:@ "UPDATE t_student SET name= ' Eric ' WHERE id=?", @4];        [DB commit];    }];}

The above because the use of the Fmdb package is good, in fact, the original code is this:

[DB executeupdate:@ "BEGIN TRANSACTION"]; [DB executeupdate:@ "ROLLBACK TRANSACTION"]; [DB executeupdate:@ "COMMIT TRANSACTION"];

In--fmdb, the queue can also be used for transactional operations, open, close, rollback transactions, etc. are already encapsulated in the queue.

-(ibaction) Update: (ID) Sender {    [self.queue indatabase:^ (Fmdatabase *db) {        [Self.queue intransaction:^ ( Fmdatabase *db, BOOL *rollback) {            [db executeupdate:@ "UPDATE t_student SET name= ' Jack ' WHERE id=?", @2];            [DB executeupdate:@ "UPDATE t_student SET name= ' Tomy ' WHERE id=?", @3];            When the situation is not found, the active rollback is made with the following statement.            *rollback=yes;            [DB executeupdate:@ "UPDATE t_student SET name= ' Eric ' WHERE id=?", @4];        }];}

iOS Development-105 SQLite third-party framework Fmdb and using Fmdatabasequeue to ensure thread safety