sqlite数据库检索

1. 数据库检索， 得到某字段下所有值

 1 - (NSArray *)selectWithColumName: (NSString *)columName
 2                        tableName: (NSString *)tableName {
 3     if ([self openDatabase] == YES) {
 4
 5         NSString * selectSQL = [NSString stringWithFormat:@"SELECT %@ FROM %@", columName, tableName];
 6         sqlite3_stmt * stmt = nil;
 7
 8         int preResult = sqlite3_prepare_v2(_db, [selectSQL UTF8String], -1, &stmt, NULL);
 9
10         if (preResult == SQLITE_OK) {
11             NSMutableArray * array = [NSMutableArray array];
12
13             while (sqlite3_step(stmt) == SQLITE_ROW) {
14                 [array addObject:[NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 0)]];
15             }
16
17             sqlite3_finalize(stmt);
18             return array;
19         } else {
20             NSLog(@"check your sqlQuery");
21             return nil;
22         }
23     } else {
24         NSLog(@"%@", [self errorWithMessage:@"openDB Failure"]);
25         return nil;
26     }
27 }

2. 通过你存储的模型以及数据表名得到所有的数据

 1 #pragma mark - select DB
 2 - (NSArray *)selectAllMembersWithTableName: (NSString *)tableName
 3                                objectModel:(id)object; {
 4     if ([self openDatabase] == YES) {
 5
 6         NSString * selectSQL = [NSString stringWithFormat:@"SELECT * FROM %@", tableName];
 7         sqlite3_stmt * stmt = nil;
 8
 9         int preResult = sqlite3_prepare_v2(_db, [selectSQL UTF8String], -1, &stmt, NULL);
10
11         if (preResult == SQLITE_OK) {
12             NSMutableArray * array = [NSMutableArray array];
13
14             while (sqlite3_step(stmt) == SQLITE_ROW) {
15
16                 id model = [[[object class] alloc] init];
17                 for (int i=0; i<sqlite3_column_count(stmt); i++) {
18                     [model setValue:[NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, i)] forKey:[NSString stringWithUTF8String:(const char *)sqlite3_column_name(stmt, i)]];
19                 }
20                 [array addObject:model];
21                 [model release];
22             }
23
24             sqlite3_finalize(stmt);
25             return array;
26         } else {
27             NSLog(@"check your sqlQuery and Model");
28             return nil;
29         }
30     } else {
31         NSLog(@"%@", [self errorWithMessage:@"SqlQuery error"]);
32         return nil;
33     }
34 }

3. 通过key：value对应关系的字典为数据库查询语句的基础， 得到需要的值

.h文件定义以及使用提示

#pragma mark selectWithSqlQueryDict
/*
 get value with sql statement
 you must give columName(dict key) = value(dict value) - all string type.
 e.g  dict = {
                "name" = "xxdbuser",
                "age"  = "19"
                };
 object: model you want
 通过包含有你的约束条件的字典、 通过表名称、 你所给的模型、 返回包含有若干模型的数组
 */
- (NSArray *)selectWithSqlQueryDictionary: (NSDictionary *)sqlQueryDictionary
                                tableName: (NSString *)tableName
                                    model: (id)object;

.m 文件实现

 1 #pragma mark selectWithSqlQuery
 2 - (NSArray *)selectWithSqlQueryDictionary: (NSDictionary *)sqlQueryDictionary
 3                                 tableName: (NSString *)tableName
 4                                     model: (id)object {
 5
 6     // getAllKeys
 7     NSArray * keyArray = sqlQueryDictionary.allKeys;
 8     NSString * sqlQuery = [NSString stringWithFormat:@"SELECT * FROM %@ WHERE ", tableName];
 9
10     if ([self openDatabase] == YES) {
11
12         // foreach build sqlQuery
13         for (NSString * key in keyArray) {
14             sqlQuery = [sqlQuery stringByAppendingString:[NSString stringWithFormat:@"%@ = ‘%@‘ and ", key, sqlQueryDictionary[key]]];
15         }
16         sqlQuery = [sqlQuery substringToIndex:[sqlQuery length] - 4];
17
18         sqlite3_stmt * stmt;
19
20         int result = sqlite3_prepare_v2(_db, [sqlQuery UTF8String], -1, &stmt, NULL);
21         if (result == SQLITE_OK) {
22             NSMutableArray * array = [NSMutableArray array];
23
24             while (sqlite3_step(stmt) == SQLITE_ROW) {
25
26                 id model = [[[object class] alloc] init];
27                 for (int i=0; i<sqlite3_column_count(stmt); i++) {
28                     [model setValue:[NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, i)] forKey:[NSString stringWithUTF8String:(const char *)sqlite3_column_name(stmt, i)]];
29                 }
30                 [array addObject:model];
31                 [model release];
32             }
33
34             sqlite3_finalize(stmt);
35             return array;
36         } else {
37             NSLog(@"check your sqlQuery");
38             return nil;
39         }
40
41     } else {
42         NSLog(@"%@", [self errorWithMessage:@"openDB Failure"]);
43         return nil;
44     }
45 }

4. 错误信息的输出

1 #pragma mark - errorMessage
2 - (NSError *)errorWithMessage:(NSString *)message {
3     return [NSError errorWithDomain:@"XXDB" code:sqlite3_errcode(_db) userInfo:[NSDictionary dictionaryWithObject:message forKey:NSLocalizedDescriptionKey]];
4 }

ok 今天就到这里。 数据库是数据持久化最常用的办法。 一定熟练掌握用户的各种需求实现的办法