I have one value which looks like this "00123-23" ,I have no idea about the datatype to be used to store in the table. So I used Text data type to store this value.But When I try to check this value, the query is saying that there is no such value in my table, but actually there is a value. Here is my query:
NSString *x_accountNo;
x_accountNo=[_substrings objectAtIndex:2]; //x_accountNo=00123-23
NSString *query_newAccount = [NSString stringWithFormat:#"SELECT * FROM MYTABLE WHERE ACCOUNT=%# ",x_accountNo];
BOOL recordExist_newAccount = [self recordExistOrNot_newAccount:query_newAccount];
if (!recordExist_newAccount) {
nslog(#"no data");
}
Everytime I execute this statement, It is giving me no data . Could you please tell me what I am doing wrong here?
You might need to have string inside quotes:
SELECT * FROM MYTABLE WHERE ACCOUNT='%#'
Related
Is it possible to execute two or more select statement in one query in SQLite? For example,
We can execute create or insert query,
NSString *create_query = #"create table if not exists Employee (id integer primary key, firstName text, lastName text);create table if not exists Department (id integer primary key, department text, devision text)";
By using,
sqlite3_exec(self.contactDB,[create_query UTF8String], NULL, NULL, &errorMessage) == SQLITE_OK)
we can execute it.
But if query is something like,
NSString *select_query = #"select * from Employee;select * from Department";
Then is it possible to execute? If yes then how to differentiate data from sqlite3_step?
Generally we are fetching data like,
if (sqlite3_prepare_v2(self.contactDB, [select_query UTF8String], -1, &statement, NULL) == SQLITE_OK) {
NSLog(#"prepared from data get");
while (sqlite3_step(statement) == SQLITE_ROW) {
NSString *department = [[NSString alloc]initWithUTF8String:(const char*)sqlite3_column_text(statement, 1)];
NSString *devision = [[NSString alloc]initWithUTF8String:(const char *)sqlite3_column_text(statement, 2)];
NSLog(#"Department : %#, Devision : %#",department,devision);
}
NSLog(#"errror1 is %s",sqlite3_errmsg(self.contactDB));
}
But if there is a two select statement then how to identify column and row in sqlite3_step?
We can execute two select statements together (i.e. select * from Employee;select * from Department ) in terminal, so it should some way in iOS I think.
Yes, you can use sqlite3_exec() to execute two SELECT statements in one call. You just have to provide a callback function where you handle the result rows. I've never used that feature, and how I understand the doc you're on your own to distinguish the rows of each statement; perhaps one can use the column count for that.
I advise against using sqlite3_exec() that way; it seems rather tedious and error-prone. sqlite3_prepare_*() should be the way to go, and it can only handle one result set (SELECT query), but you can have open multiple statements at a time, represented by the ppStmt handle. If you have problems with that you should describe them instead of posting a XY Problem question.
We can perform this by using C style callback function with sqlite3_exec.
There is no proper code available on internet (I haven't found!) so i would like to answer with code sample.
We can implement C - style callback method like
int myCallback(void *parameter, int numberOfColumn, char **resultArr, char **column)
{
NSLog(#"number of column %d",numberOfColumn); // numberOfColumn is return total number of column for correspond table
NSString *columnName = [[NSString alloc]initWithUTF8String:column[0]]; // This will return column name column[0] is for first, column[1] for second column etc
NSLog(#"column name is %#",columnName);
NSString *result = [[NSString alloc]initWithUTF8String:resultArr[2]]; // resultArr returns value for row with respactive column for correspond table. resultArr[2] considered as third column.
NSLog(#"result is %#",result);
return 0;
}
And we can call this callback function in our sqlite3_exec function like,
NSString *getData = #"select * from Department;select * from Employee";
if (sqlite3_exec(self.contactDB, [getData UTF8String], myCallback, (__bridge void *)(self), &err) == SQLITE_OK ) {
if (err) {
NSLog(#"error : %s",err);
}
else {
NSLog(#"executed sucessfully");
}
}
We have make bride : (__bridge void *)(self) as parameter of sqlite3_exec. We can pass NULL in this case because we have implemented c style function. But if we implement Objective - c style function or method then we must pass (__bridge void *)(self) as parameter.
So, By callback function we can execute multiple queries in one statement whether it is select type queries or else.
Reference : One-Step Query Execution Interface
I need to know if there is a way to use if statements to display certain nsstrings, depending on whether or not that NSString contains any data.
I have an nsstringcalled visitorInfo.
The string uses data from other strings (i.e. which operating system the user is running) and displays that info. Here is an example of what I'm talking about:
NSString *visitorInfo = [NSString stringWithFormat:#"INFO\n\nVisitor Location\n%#\n\nVisitor Blood Type\n\%#", _visitor.location, _visitor.bloodType];
And it would display like this:
INFO
Location
Miami, FL
Blood Type
O positive
However, I have several pieces of data that only load if the user chooses to do so. i.e their email address.
This section of code below would do what I want, but my visitorInfo string contains tons of different strings, and if I use this code below, then it won't load any of them if the user chooses not to submit his blood type.
if ([self.visitor.bloodType length] > 0) {
NSString *visitorInfo = [NSString stringWithFormat:#"INFO\n\nVisitor Location\n%#\n\nVisitor Blood Type\n\%#", _visitor.location, _visitor.bloodType];
}
So basically if their is data stored in bloodType then i went that code to run, but if there isn't any data I only want it to skip over bloodType, and finish displaying the rest of the data.
Let me know if you have any more questions
Additional details. I'm using an NSString for a specific reason, which is why I'm not using a dictionary.
Just build up the string as needed using NSMutableString:
NSMutableString *visitorInfo = [NSMutableString stringWithFormat:#"INFO\n\nVisitor Location\n%#, _visitor.location];
if ([self.visitor.bloodType length] > 0) {
[visitorInfo appendFormat:#"\n\nVisitor Blood Type\n\%#", _visitor.bloodType];
}
You can check if a string has any data in it by using the following
if([_visitor.location length]<1){
//This means there's no data and is a better way of checking, rather than isEqualToString:#"".
}else{
//there is some date here
}
** EDIT - (just re-reading your question, sorry this answer is dependant on _visitor.location being a string in the first place)*
I hope this helps
Try this -
NSString *str = #"INFO";
if (_visitor.location) {
str = [NSString stringWithFormat:#"\n\nVisitor Location\n%#",_visitor.location];
}
if (_visitor.bloodType) {
str = [NSString stringWithFormat:#"\n\nVisitor Blood Type\n\%#",_visitor.bloodType];
}
Is it possible to bind a parameter in the FROM clause of a query to SQLite? How?
If not, why? Any alternatives?
Here is what I want to do in my iOS application:
- (BOOL)existsColumn:(NSString *)column inTable:(NSString *)table ofDatabase:(FMDatabase *)database {
NSString *query = #"SELECT ? FROM ? LIMIT 0";
NSArray *queryParameters = #[column, table];
return (BOOL)[database executeQuery:query withArgumentsInArray:queryParameters];
}
Here is the error message I get:
near "?": syntax error
I understand that there are other ways to check if a column exists. I am specifically curious why I can't bind a parameter in the FROM clause (only binding a parameter in the SELECT clause above works so it must be an issue with the FROM clause).
The ? should only be used for binding actual values into the query such in the VALUES section of an INSERT or values in a WHERE clause.
For dynamically building the column and table names you should simply use a string format to build the query string before sending it to FMDB.
- (BOOL)existsColumn:(NSString *)column inTable:(NSString *)table ofDatabase:(FMDatabase *)database {
NSString *query = [NSString stringWithFormat:#"SELECT %# FROM %# LIMIT 0", column, table];
return (BOOL)[database executeQuery:query];
}
Please note that you should not use the string format in place of using ? and proper value binding for actual values (which you don't have in this case).
I'm hoping someone here might be able to help me out.
I need to insert a NSMutableDictionary into one cell of a SQLite database. I am able to insert strings etc into the database, but when I try and insert a Dictionary I get a syntax error:
**Can't run query 'BEGIN TRANSACTION; UPDATE Database SET Column1 = {
Bad = "";
"End_Time" = 4;
Good = "";
Moderate = "";
Note = "";
} WHERE Title = Name; COMMIT TRANSACTION;' error message: unrecognized token: "{"**
To do this I am using the following code:
NSString *sql2 = [NSString stringWithFormat:#"UPDATE Database SET Column%# = %# WHERE Title = %#",previousQuestion,adictionary,Name];
Can anyone help or suggest a different approach,? I need to be able to store the key/values in 1 cell, as there will be 79 more cells with similar data and I need to reference each specific key from a specific column of the database.
I've tried turning the Dictionary into a string (and then I'd turn the string back to a dictionary on retrieval) But this causes the same issue.
Any suggestions?
Many thanks,
Andrew
Their is two way you can do this.
1st way :-
Archive your NSMutableDictionary convert it into NSData and store it in your Sqlite column which datatype should have be blob type. Archiving something like this,
NSData *theDictionaryData = [NSKeyedArchiver archivedDataWithRootObject:yourDictionary];
Bind this data in sqlite,
sqlite3_bind_blob(addStmt, 5, theDictionaryData, -1, SQLITE_TRANSIENT);
Now retrieving time from sqlite,
NSData *retrieveData = [[NSData alloc] initWithBytes:sqlite3_column_blob(selectstmt, 4) length:sqlite3_column_bytes(selectstmt, 4)];
and finally convert it into NSDictionary,
NSDictionary *dictionary = [NSKeyedUnarchiver unarchiveObjectWithData:retrieveData];
2nd way :-
Create numbers of column those are equal to numbers of keys of NSDictionary. Bring data from every key and save it respective table column.
You can't just insert an Objective-C object into the database. It must be a string, binary data, or a number. In converting it to a string, you also need to sanitize the input (so that it doesn't contain any invalid characters that SQL will interpret in another way). For example, if you tried to insert a string that was some SQL code, you wouldn't want it to try to execute that code. It looks like here it's getting hung up on a { in the string. You could instead convert the dictionary or the string to NSData and insert it into the database as binary data.
I'm using FMDB to create a SQLite database on iPhone. I have a initial.sql that is of the form
CREATE TABLE Abc ... ;
CREATE TABLE Def ... ;
I load this by loading the file into an NSString and running it
NSString * str = // string from file initial.sql
[db executeUpdate: str];
This succeeds but later on I get a failure:
no such table: Def
It's clear that the second statement is not being called. How can I do this so that all of the queries will be called?
According to the SQLite documentation:
"The routines sqlite3_prepare_v2(), sqlite3_prepare(), sqlite3_prepare16(), sqlite3_prepare16_v2(), sqlite3_exec(), and sqlite3_get_table() accept an SQL statement list (sql-stmt-list) which is a semicolon-separated list of statements."
So, this should all work.
I got bitten by this one too; it took me an entire morning of stepping through FMDatabase and reading the sqlite3 API documentation to find it. I am still not entirely sure about the root cause of the issue, but according to this bug in PHP, it is necessary to call sqlite3_exec instead of preparing the statement with sqlite3_prepare_v2 and then calling sqlite3_step.
The documentation does not seem to suggest that this behaviour would happen, hence our confusion, and I would love for someone with more experience with sqlite to come forward with some hypotheses.
I solved this by developing a method to execute a batch of queries. Please find the code below. If you prefer, you could rewrite this into a category instead of just adding it to FMDatabase.h, your call.
Add this to the FMDatabase interface in FMDatabase.h:
- (BOOL)executeBatch:(NSString*)sql error:(NSError**)error;
Add this to the FMDatabase implementation in FMDatabase.m:
- (BOOL)executeBatch:(NSString *)sql error:(NSError**)error
{
char* errorOutput;
int responseCode = sqlite3_exec(db, [sql UTF8String], NULL, NULL, &errorOutput);
if (errorOutput != nil)
{
*error = [NSError errorWithDomain:[NSString stringWithUTF8String:errorOutput]
code:responseCode
userInfo:nil];
return false;
}
return true;
}
Please note that there are many features missing from executeBatch which make it unsuitable for a lot of purposes. Specifically, it doesn't check to see if the database is locked, it doesn't make sure FMDatabase itself isn't locked, it doesn't support statement caching.
If you need that, the above is a good starting point to code it yourself. Happy hacking!
FMDB v2.3 now has a native wrapper for sqlite3_exec called executeStatements:
BOOL success;
NSString *sql = #"create table bulktest1 (id integer primary key autoincrement, x text);"
"create table bulktest2 (id integer primary key autoincrement, y text);"
"create table bulktest3 (id integer primary key autoincrement, z text);"
"insert into bulktest1 (x) values ('XXX');"
"insert into bulktest2 (y) values ('YYY');"
"insert into bulktest3 (z) values ('ZZZ');";
success = [db executeStatements:sql];
It also has a variant that employs the sqlite3_exec callback, implemented as a block:
sql = #"select count(*) as count from bulktest1;"
"select count(*) as count from bulktest2;"
"select count(*) as count from bulktest3;";
success = [db executeStatements:sql withResultBlock:^int(NSDictionary *dictionary) {
NSInteger count = [dictionary[#"count"] integerValue];
NSLog(#"Count = %d", count);
return 0; // if you return 0, it continues execution; return non-zero, it stops execution
}];
Split Batch Statement
Add in .h file:
#import "FMSQLStatementSplitter.h"
#import "FMDatabaseQueue.h"
FMSQLStatementSplitter can split batch sql statement into several separated statements, then [FMDatabase executeUpdate:] or other methods can be used to execute each separated statement:
FMDatabaseQueue *queue = [FMDatabaseQueue databaseQueueWithPath:databasePath];
NSString *batchStatement = #"insert into ftest values ('hello;');"
#"insert into ftest values ('hi;');"
#"insert into ftest values ('not h!\\\\');"
#"insert into ftest values ('definitely not h!')";
NSArray *statements = [[FMSQLStatementSplitter sharedInstance] statementsFromBatchSqlStatement:batchStatement];
[queue inDatabase:^(FMDatabase *adb) {
for (FMSplittedStatement *sqlittedStatement in statements)
{
[adb executeUpdate:sqlittedStatement.statementString];
}
}];