使用 SQLiteManager 操作 sqlite3 数据库

SQLiteManager  

https://github.com/misato/SQLiteManager4iOS

      本人以前从事过嵌入式开发,后来转职为iOS开发,即使如此,也绝不想去碰C语言级别的面向过程的 sqlite3 来操作数据库,做高级语言开发还去折腾面向过程的东西,一个小小的nil没判断好就导致程序崩溃, 这就是 sqlite3 APIs 给你带来的问题,只有封装成面向对象的接口才有可能会去用.有一个封装得挺好的 FMDB 是不二的选择,但这个 SQLiteManager 属于轻量级封装,满足了最最基本的需求,但是,他是在开了ARC的情形下使用的,也就是说,没开ARC后会各种泄露......

      上面的链接可以下载源码,我修改了源码,适用于我自己,提供如下:

SQLiteManager.h

#import <Foundation/Foundation.h>
#import "sqlite3.h"


enum errorCodes {
    kDBNotExists,
    kDBFailAtOpen, 
    kDBFailAtCreate,
    kDBErrorQuery,
    kDBFailAtClose
};

@interface SQLiteManager : NSObject {

    sqlite3 *db; // The SQLite db reference
    NSString *databaseName; // The database name
}

- (id)initWithDatabaseNamed:(NSString *)name;

// SQLite Operations
- (NSError *) openDatabase;
- (NSError *) doQuery:(NSString *)sql;
- (NSError *)doUpdateQuery:(NSString *)sql withParams:(NSArray *)params;
- (NSArray *) getRowsForQuery:(NSString *)sql;
- (NSError *) closeDatabase;
- (NSInteger)getLastInsertRowID;

- (NSString *)getDatabaseDump;

@end

SQLiteManager.m

#import "SQLiteManager.h"


#define FOLDER_PATH   @"/Library/Caches/YOU_FOLDER_NAME"


// Private methods
@interface SQLiteManager (Private)

- (NSString *)getDatabasePath;
- (NSError *)createDBErrorWithDescription:(NSString*)description andCode:(int)code;

@end



@implementation SQLiteManager

#pragma mark Init & Dealloc

/**
 * Init method.
 * Use this method to initialise the object, instead of just "init".
 *
 * @param name the name of the database to manage.
 *
 * @return the SQLiteManager object initialised.
 */

- (id)initWithDatabaseNamed:(NSString *)name; {
    self = [super init];
    if (self != nil) {
        databaseName = [[NSString alloc] initWithString:name];
        db = nil;
    }
    return self;
}

#pragma mark SQLite Operations

/**
 * Open or create a SQLite3 database.
 *
 * If the db exists, then is opened and ready to use. If not exists then is created and opened.
 *
 * @return nil if everything was ok, an NSError in other case.
 *
 */

- (NSError *) openDatabase {
    
    NSError *error = nil;
    
    NSString *databasePath = [self getDatabasePath];
    NSLog(@"%@", databasePath);
    
    const char *dbpath = [databasePath UTF8String];
    int result = sqlite3_open(dbpath, &db);
    if (result != SQLITE_OK) {
        const char *errorMsg = sqlite3_errmsg(db);
        NSString *errorStr = [NSString stringWithFormat:@"The database could not be opened: %@",[NSString stringWithCString:errorMsg encoding:NSUTF8StringEncoding]];
        error = [self createDBErrorWithDescription:errorStr    andCode:kDBFailAtOpen];
    }
    
    return error;
}


/**
 * Does an SQL query.
 *
 * You should use this method for everything but SELECT statements.
 *
 * @param sql the sql statement.
 *
 * @return nil if everything was ok, NSError in other case.
 */

- (NSError *)doQuery:(NSString *)sql {
    
    NSError *openError = nil;
    NSError *errorQuery = nil;
    
    //Check if database is open and ready.
    if (db == nil) {
        openError = [self openDatabase];
    }
    
    if (openError == nil) {
        sqlite3_stmt *statement;
        const char *query = [sql UTF8String];
        sqlite3_prepare_v2(db, query, -1, &statement, NULL);
        
        if (sqlite3_step(statement) == SQLITE_ERROR) {
            const char *errorMsg = sqlite3_errmsg(db);
            errorQuery = [self createDBErrorWithDescription:[NSString stringWithCString:errorMsg encoding:NSUTF8StringEncoding]
                                                    andCode:kDBErrorQuery];
        }
        sqlite3_finalize(statement);
        errorQuery = [self closeDatabase];
    }
    else {
        errorQuery = openError;
    }
    
    return errorQuery;
}

/**
 * Does an SQL parameterized query.
 *
 * You should use this method for parameterized INSERT or UPDATE statements.
 *
 * @param sql the sql statement using ? for params.
 *
 * @param params NSArray of params type (id), in CORRECT order please.
 *
 * @return nil if everything was ok, NSError in other case.
 */

- (NSError *)doUpdateQuery:(NSString *)sql withParams:(NSArray *)params {
    
    NSError *openError = nil;
    NSError *errorQuery = nil;
    
    //Check if database is open and ready.
    if (db == nil) {
        openError = [self openDatabase];
    }
    
    if (openError == nil) {
        sqlite3_stmt *statement;
        const char *query = [sql UTF8String];
        sqlite3_prepare_v2(db, query, -1, &statement, NULL);
        
        //BIND the params!
        int count =0;
        for (id param in params ) {
            count++;
            if ([param isKindOfClass:[NSString class]] )
                sqlite3_bind_text(statement, count, [param UTF8String], -1, SQLITE_TRANSIENT);
            if ([param isKindOfClass:[NSNumber class]] ) {
                if (!strcmp([param objCType], @encode(float)))
                    sqlite3_bind_double(statement, count, [param doubleValue]);
                else if (!strcmp([param objCType], @encode(int)))
                    sqlite3_bind_int(statement, count, [param intValue]);
                else if (!strcmp([param objCType], @encode(BOOL)))
                    sqlite3_bind_int(statement, count, [param intValue]);
                else
                    NSLog(@"unknown NSNumber");
            }
            if ([param isKindOfClass:[NSDate class]]) {
               sqlite3_bind_double(statement, count, [param timeIntervalSince1970]);
            }
            if ([param isKindOfClass:[NSData class]] ) {
                sqlite3_bind_blob(statement, count, [param bytes], [param length], SQLITE_STATIC);
            }
        }
        
        if (sqlite3_step(statement) == SQLITE_ERROR) {
            const char *errorMsg = sqlite3_errmsg(db);
            errorQuery = [self createDBErrorWithDescription:[NSString stringWithCString:errorMsg encoding:NSUTF8StringEncoding]
                                                    andCode:kDBErrorQuery];
        }
        sqlite3_finalize(statement);
        errorQuery = [self closeDatabase];
    }
    else {
        errorQuery = openError;
    }
    
    return errorQuery;
}

- (NSInteger)getLastInsertRowID {

    NSError *openError = nil;
    
    sqlite3_int64 rowid = 0;
    
    //Check if database is open and ready.
    if (db == nil) {
        openError = [self openDatabase];
    }
    
    if (openError == nil) {
        rowid = sqlite3_last_insert_rowid(db);
    }
    
    return (NSInteger)rowid;
}

/**
 * Does a SELECT query and gets the info from the db.
 *
 * The return array contains an NSDictionary for row, made as: key=columName value= columnValue.
 *
 * For example, if we have a table named "users" containing:
 * name | pass
 * -------------
 * admin| 1234
 * pepe | 5678
 *
 * it will return an array with 2 objects:
 * resultingArray[0] = name=admin, pass=1234;
 * resultingArray[1] = name=pepe, pass=5678;
 *
 * So to get the admin password:
 * [[resultingArray objectAtIndex:0] objectForKey:@"pass"];
 *
 * @param sql the sql query (remember to use only a SELECT statement!).
 *
 * @return an array containing the rows fetched.
 */

- (NSArray *)getRowsForQuery:(NSString *)sql {
    
    NSMutableArray *resultsArray = [[NSMutableArray alloc] initWithCapacity:1];
    
    if (db == nil) {
        [self openDatabase];
    }
    
    sqlite3_stmt *statement;
    const char *query = [sql UTF8String];
    int returnCode = sqlite3_prepare_v2(db, query, -1, &statement, NULL);
    
    if (returnCode == SQLITE_ERROR) {
        const char *errorMsg = sqlite3_errmsg(db);
        NSError *errorQuery = [self createDBErrorWithDescription:[NSString stringWithCString:errorMsg encoding:NSUTF8StringEncoding]
                                                         andCode:kDBErrorQuery];
        NSLog(@"%@", errorQuery);
    }
    
    while (sqlite3_step(statement) == SQLITE_ROW) {
        int columns = sqlite3_column_count(statement);
        NSMutableDictionary *result = [[NSMutableDictionary alloc] initWithCapacity:columns];
        
        for (int i = 0; i<columns; i++) {
            const char *name = sqlite3_column_name(statement, i);
            
            NSString *columnName = [NSString stringWithCString:name encoding:NSUTF8StringEncoding];
            
            int type = sqlite3_column_type(statement, i);
            
            switch (type) {
                case SQLITE_INTEGER:
                {
                    int value = sqlite3_column_int(statement, i);
                    [result setObject:[NSNumber numberWithInt:value] forKey:columnName];
                    break;
                }
                case SQLITE_FLOAT:
                {
                    float value = sqlite3_column_double(statement, i);
                    [result setObject:[NSNumber numberWithFloat:value] forKey:columnName];
                    break;
                }
                case SQLITE_TEXT:
                {
                    const char *value = (const char*)sqlite3_column_text(statement, i);
                    [result setObject:[NSString stringWithCString:value encoding:NSUTF8StringEncoding] forKey:columnName];
                    break;
                }
                    
                case SQLITE_BLOB:
                {
                    int bytes = sqlite3_column_bytes(statement, i);
                    if (bytes > 0) {
                        const void *blob = sqlite3_column_blob(statement, i);
                        if (blob != NULL) {
                            [result setObject:[NSData dataWithBytes:blob length:bytes] forKey:columnName];
                        }
                    }
                    break;
                }
                    
                case SQLITE_NULL:
                    [result setObject:[NSNull null] forKey:columnName];
                    break;
                    
                default:
                {
                    const char *value = (const char *)sqlite3_column_text(statement, i);
                    [result setObject:[NSString stringWithCString:value encoding:NSUTF8StringEncoding] forKey:columnName];
                    break;
                }
                    
            } //end switch
            
            
        } //end for
        
        [resultsArray addObject:result];
        
    } //end while
    sqlite3_finalize(statement);
    
    [self closeDatabase];
    
    return resultsArray;
    
}


/**
 * Closes the database.
 *
 * @return nil if everything was ok, NSError in other case.
 */

- (NSError *) closeDatabase {
    
    NSError *error = nil;
    
    
    if (db != nil) {
        if (sqlite3_close(db) != SQLITE_OK){
            const char *errorMsg = sqlite3_errmsg(db);
            NSString *errorStr = [NSString stringWithFormat:@"The database could not be closed: %@",[NSString stringWithCString:errorMsg encoding:NSUTF8StringEncoding]];
            error = [self createDBErrorWithDescription:errorStr andCode:kDBFailAtClose];
        }
        
        db = nil;
    }
    
    return error;
}


/**
 * Creates an SQL dump of the database.
 *
 * This method could get a csv format dump with a few changes.
 * But i prefer working with sql dumps ;)
 *
 * @return an NSString containing the dump.
 */

- (NSString *)getDatabaseDump {
    
    NSMutableString *dump = [[NSMutableString alloc] initWithCapacity:256];
    
    // info string ;) please do not remove it
    [dump appendString:@";\n; Dump generated with SQLiteManager4iOS \n;\n; By Misato (2011)\n"];
    [dump appendString:[NSString stringWithFormat:@"; database %@;\n", [databaseName lastPathComponent]]];
    
    // first get all table information
    
    NSArray *rows = [self getRowsForQuery:@"SELECT * FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%';"];
    // last sql query returns something like:
    // {
    // name = users;
    // rootpage = 2;
    // sql = "CREATE TABLE users (id integer primary key autoincrement, user text, password text)";
    // "tbl_name" = users;
    // type = table;
    // }
    
    //loop through all tables
    for (int i = 0; i<[rows count]; i++) {
        
        NSDictionary *obj = [rows objectAtIndex:i];
        //get sql "create table" sentence
        NSString *sql = [obj objectForKey:@"sql"];
        [dump appendString:[NSString stringWithFormat:@"%@;\n",sql]];
        
        //get table name
        NSString *tableName = [obj objectForKey:@"name"];
        
        //get all table content
        NSArray *tableContent = [self getRowsForQuery:[NSString stringWithFormat:@"SELECT * FROM %@",tableName]];
        
        for (int j = 0; j<[tableContent count]; j++) {
            NSDictionary *item = [tableContent objectAtIndex:j];
            
            //keys are column names
            NSArray *keys = [item allKeys];
            
            //values are column values
            NSArray *values = [item allValues];
            
            //start constructing insert statement for this item
            [dump appendString:[NSString stringWithFormat:@"insert into %@ (",tableName]];
            
            //loop through all keys (aka column names)
            NSEnumerator *enumerator = [keys objectEnumerator];
            id obj;
            while (obj = [enumerator nextObject]) {
                [dump appendString:[NSString stringWithFormat:@"%@,",obj]];
            }
            
            //delete last comma
            NSRange range;
            range.length = 1;
            range.location = [dump length]-1;
            [dump deleteCharactersInRange:range];
            [dump appendString:@") values ("];
            
            // loop through all values
            // value types could be:
            // NSNumber for integer and floats, NSNull for null or NSString for text.
            
            enumerator = [values objectEnumerator];
            while (obj = [enumerator nextObject]) {
                //if it's a number (integer or float)
                if ([obj isKindOfClass:[NSNumber class]]){
                    [dump appendString:[NSString stringWithFormat:@"%@,",[obj stringValue]]];
                }
                //if it's a null
                else if ([obj isKindOfClass:[NSNull class]]){
                    [dump appendString:@"null,"];
                }
                //else is a string ;)
                else{
                    [dump appendString:[NSString stringWithFormat:@"'%@',",obj]];
                }
                
            }
            
            //delete last comma again
            range.length = 1;
            range.location = [dump length]-1;
            [dump deleteCharactersInRange:range];
            
            //finish our insert statement
            [dump appendString:@");\n"];
            
        }
        
    }
    
    return dump;
}

@end


#pragma mark -
@implementation SQLiteManager (Private)

/**
 * Gets the database file path (in NSDocumentDirectory).
 *
 * @return the path to the db file.
 */

- (NSString *)getDatabasePath{
    
    if([[NSFileManager defaultManager] fileExistsAtPath:databaseName]){
        // Already Full Path
        return databaseName;
    } else {
        // 判断文件夹是否存在,不存在则创建文件夹
        NSString *docsDir = [NSHomeDirectory() stringByAppendingString:FOLDER_PATH];
        if (SQLiteManager_fileOrFolderExistFromSandbox(docsDir) == NO) {
            SQLiteManager_createFolderForSandbox(docsDir);
        }
        
        return [docsDir stringByAppendingPathComponent:databaseName];
    }
}

#pragma mark 沙盒中创建文件夹
BOOL SQLiteManager_createFolderForSandbox(NSString *filePath)
{
    return [[NSFileManager defaultManager] createDirectoryAtPath:filePath
                                     withIntermediateDirectories:YES attributes:nil error:nil];
}

#pragma mark 文件或者文件夹是否存在
BOOL SQLiteManager_fileOrFolderExistFromSandbox(NSString *filePath)
{
    return [[NSFileManager defaultManager] fileExistsAtPath:filePath isDirectory:NO];
}

/**
 * Creates an NSError.
 *
 * @param description the description wich can be queried with [error localizedDescription];
 * @param code the error code (code erors are defined as enum in the header file).
 *
 * @return the NSError just created.
 *
 */

- (NSError *)createDBErrorWithDescription:(NSString*)description andCode:(int)code {
    
    NSDictionary *userInfo = [[NSDictionary alloc] initWithObjectsAndKeys:description, NSLocalizedDescriptionKey, nil];
    NSError *error = [NSError errorWithDomain:@"SQLite Error" code:code userInfo:userInfo];
    
    return error;
}

@end

以下是增删改查以及常规操作:

打开数据库

    //打开数据库
    SQLiteManager *dbManager = [[SQLiteManager alloc] initWithDatabaseNamed:@"Y.X.db"];

创建表

    NSError *error = nil;
    //创建表
    /*
     id        int    主键
     user      text
     password  text
     */
    error = [dbManager doQuery:@"CREATE TABLE IF NOT EXISTS users (id integer primary key autoincrement, user text, password text);"];
    if (error != nil) {
        NSLog(@"Error: %@",[error localizedDescription]);
    }

插入

    //在表中插入一条记录
    error =  [dbManager doQuery:@"insert into users (user, password) values ('YouXian','19871220');"];
    if (error != nil) {
        NSLog(@"Error: %@",[error localizedDescription]);
    }

查询

    //查询记录
    [[dbManager getRowsForQuery:@"SELECT * FROM users"] enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        NSLog(@"%@", obj);
    }];

修改

    //修改一条记录
    error =  [dbManager doQuery:@"update users set user = 'YX',password = '1' where id = 1;"];
    if (error != nil) {
        NSLog(@"Error: %@",[error localizedDescription]);
    }

删除

    //删除一条记录
    error =  [dbManager doQuery:@"delete from users where id = 1;"];
    if (error != nil) {
        NSLog(@"Error: %@",[error localizedDescription]);
    }

 

心得:

      如果觉得自己想去捣鼓 C 语言级别的 API 不怕崩溃,可以去试试,对于我而言,不是我对其不感兴趣不愿意研究他,只是,在对性能没有要求的前提下花精力去造车轮子完全没有必要,真心话.