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	<option value="//api/name/close">&nbsp;&nbsp;&nbsp;&nbsp;- close</option>
	
	<option value="//api/name/inDatabase:">&nbsp;&nbsp;&nbsp;&nbsp;- inDatabase:</option>
	
	<option value="//api/name/inDeferredTransaction:">&nbsp;&nbsp;&nbsp;&nbsp;- inDeferredTransaction:</option>
	
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	<li><span class="nodisclosure"></span><span class="sectionName"><a href="#task_Initialization, opening, and closing of queue">Initialization, opening, and closing of queue</a></span></li>
	
	<li><span class="nodisclosure"></span><span class="sectionName"><a href="#task_Dispatching database operations to queue">Dispatching database operations to queue</a></span></li>
	
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	<li><span class="nodisclosure"></span><span class="sectionName"><a href="#//api/name/databaseQueueWithPath:">databaseQueueWithPath:</a></span></li>
	
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	<li><span class="nodisclosure"></span><span class="sectionName"><a href="#//api/name/close">close</a></span></li>
	
	<li><span class="nodisclosure"></span><span class="sectionName"><a href="#//api/name/inDatabase:">inDatabase:</a></span></li>
	
	<li><span class="nodisclosure"></span><span class="sectionName"><a href="#//api/name/inDeferredTransaction:">inDeferredTransaction:</a></span></li>
	
	<li><span class="nodisclosure"></span><span class="sectionName"><a href="#//api/name/inSavePoint:">inSavePoint:</a></span></li>
	
	<li><span class="nodisclosure"></span><span class="sectionName"><a href="#//api/name/inTransaction:">inTransaction:</a></span></li>
	
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						<h1 class="title title-header">FMDatabaseQueue Class Reference</h1>
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					<div class="section section-specification"><table cellspacing="0"><tbody>
						<tr>
	<td class="specification-title">Inherits from</td>
	<td class="specification-value">NSObject</td>
</tr><tr>
	<td class="specification-title">Declared in</td>
	<td class="specification-value">FMDatabaseQueue.h<br />FMDatabaseQueue.m</td>
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					<div class="section section-overview">
						<a title="Overview" name="overview"></a>
						<h2 class="subtitle subtitle-overview">Overview</h2>
						<p>To perform queries and updates on multiple threads, you&rsquo;ll want to use <code>FMDatabaseQueue</code>.</p>

<p>Using a single instance of <a href="../Classes/FMDatabase.html"><code>FMDatabase</code></a> from multiple threads at once is a bad idea.  It has always been OK to make a <a href="../Classes/FMDatabase.html"><code>FMDatabase</code></a> object <em>per thread</em>.  Just don&rsquo;t share a single instance across threads, and definitely not across multiple threads at the same time.</p>

<p>Instead, use <code>FMDatabaseQueue</code>. Here&rsquo;s how to use it:</p>

<p>First, make your queue.</p>

<pre><code>FMDatabaseQueue *queue = [FMDatabaseQueue databaseQueueWithPath:aPath];
</code></pre>

<p>Then use it like so:</p>

<pre><code>[queue inDatabase:^(FMDatabase *db) {
    [db executeUpdate:@"INSERT INTO myTable VALUES (?)", [NSNumber numberWithInt:1]];
    [db executeUpdate:@"INSERT INTO myTable VALUES (?)", [NSNumber numberWithInt:2]];
    [db executeUpdate:@"INSERT INTO myTable VALUES (?)", [NSNumber numberWithInt:3]];

    FMResultSet *rs = [db executeQuery:@"select * from foo"];
    while ([rs next]) {
        //…
    }
}];
</code></pre>

<p>An easy way to wrap things up in a transaction can be done like this:</p>

<pre><code>[queue inTransaction:^(FMDatabase *db, BOOL *rollback) {
    [db executeUpdate:@"INSERT INTO myTable VALUES (?)", [NSNumber numberWithInt:1]];
    [db executeUpdate:@"INSERT INTO myTable VALUES (?)", [NSNumber numberWithInt:2]];
    [db executeUpdate:@"INSERT INTO myTable VALUES (?)", [NSNumber numberWithInt:3]];

    if (whoopsSomethingWrongHappened) {
        *rollback = YES;
        return;
    }
    // etc…
    [db executeUpdate:@"INSERT INTO myTable VALUES (?)", [NSNumber numberWithInt:4]];
}];
</code></pre>

<p><code>FMDatabaseQueue</code> will run the blocks on a serialized queue (hence the name of the class).  So if you call <code>FMDatabaseQueue</code>&rsquo;s methods from multiple threads at the same time, they will be executed in the order they are received.  This way queries and updates won&rsquo;t step on each other&rsquo;s toes, and every one is happy.</p>

<h3>See also</h3>

<ul>
<li><a href="../Classes/FMDatabase.html"><code>FMDatabase</code></a></li>
</ul>
<div class="warning"><p><strong>Warning:</strong> Do not instantiate a single <a href="../Classes/FMDatabase.html"><code>FMDatabase</code></a> object and use it across multiple threads. Use <code>FMDatabaseQueue</code> instead.</p></div><div class="warning"><p><strong>Warning:</strong> The calls to <code>FMDatabaseQueue</code>&rsquo;s methods are blocking.  So even though you are passing along blocks, they will <strong>not</strong> be run on another thread.</p></div>
					</div>
					
					
					<div class="section section-tasks">
						<a title="Tasks" name="tasks"></a>
						<h2 class="subtitle subtitle-tasks">Tasks</h2>
						
						
						<a title="Initialization, opening, and closing of queue" name="task_Initialization, opening, and closing of queue"></a>
						<h3 class="subsubtitle task-title">Initialization, opening, and closing of queue</h3>

						<ul class="task-list">
							<li>
	<span class="tooltip">
		<code><a href="#//api/name/databaseQueueWithPath:">+&nbsp;databaseQueueWithPath:</a></code>
		<span class="tooltip"><p>Create queue using path.</p></span>
	</span>
	
	
</li><li>
	<span class="tooltip">
		<code><a href="#//api/name/initWithPath:">&ndash;&nbsp;initWithPath:</a></code>
		<span class="tooltip"><p>Create queue using path.</p></span>
	</span>
	
	
</li><li>
	<span class="tooltip">
		<code><a href="#//api/name/close">&ndash;&nbsp;close</a></code>
		<span class="tooltip"><p>Close database used by queue.</p></span>
	</span>
	
	
</li>
						</ul>
						
						
						<a title="Dispatching database operations to queue" name="task_Dispatching database operations to queue"></a>
						<h3 class="subsubtitle task-title">Dispatching database operations to queue</h3>

						<ul class="task-list">
							<li>
	<span class="tooltip">
		<code><a href="#//api/name/inDatabase:">&ndash;&nbsp;inDatabase:</a></code>
		<span class="tooltip"><p>Synchronously perform database operations on queue.</p></span>
	</span>
	
	
</li><li>
	<span class="tooltip">
		<code><a href="#//api/name/inTransaction:">&ndash;&nbsp;inTransaction:</a></code>
		<span class="tooltip"><p>Synchronously perform database operations on queue, using transactions.</p></span>
	</span>
	
	
</li><li>
	<span class="tooltip">
		<code><a href="#//api/name/inDeferredTransaction:">&ndash;&nbsp;inDeferredTransaction:</a></code>
		<span class="tooltip"><p>Synchronously perform database operations on queue, using deferred transactions.</p></span>
	</span>
	
	
</li><li>
	<span class="tooltip">
		<code><a href="#//api/name/inSavePoint:">&ndash;&nbsp;inSavePoint:</a></code>
		<span class="tooltip"><p>Synchronously perform database operations using save point.</p></span>
	</span>
	
	
</li>
						</ul>
						
					</div>
					
					
					<div class="section section-methods">
						<a title="Class Methods" name="class_methods"></a>
						<h2 class="subtitle subtitle-methods">Class Methods</h2>
						
						<div class="section-method">
	<a name="//api/name/databaseQueueWithPath:" title="databaseQueueWithPath:"></a>
	<h3 class="subsubtitle method-title">databaseQueueWithPath:</h3>
	
	
	<div class="method-subsection brief-description">
		<p>Create queue using path.</p>
	</div>		
	
    
	<div class="method-subsection method-declaration"><code>+ (instancetype)databaseQueueWithPath:(NSString *)<em>aPath</em></code></div>

    
	<div class="method-subsection arguments-section parameters">
		<h4 class="method-subtitle parameter-title">Parameters</h4>
		
		<dl class="argument-def parameter-def">
			<dt><em>aPath</em></dt>
			<dd><p>The file path of the database.</p></dd>
		</dl>
		
	</div>
	
	
	<div class="method-subsection return">
		<h4 class="method-subtitle parameter-title">Return Value</h4>
		<p>The <code>FMDatabaseQueue</code> object. <code>nil</code> on error.</p>
	</div>
	
	
	<div class="method-subsection declared-in-section">
		<h4 class="method-subtitle">Declared In</h4>
		<code class="declared-in-ref">FMDatabaseQueue.h</code><br />
	</div>				
	
	
</div>
						
					</div>
					
					
					<div class="section section-methods">
						<a title="Instance Methods" name="instance_methods"></a>
						<h2 class="subtitle subtitle-methods">Instance Methods</h2>
						
						<div class="section-method">
	<a name="//api/name/close" title="close"></a>
	<h3 class="subsubtitle method-title">close</h3>
	
	
	<div class="method-subsection brief-description">
		<p>Close database used by queue.</p>
	</div>		
	
    
	<div class="method-subsection method-declaration"><code>- (void)close</code></div>

    
	<div class="method-subsection declared-in-section">
		<h4 class="method-subtitle">Declared In</h4>
		<code class="declared-in-ref">FMDatabaseQueue.h</code><br />
	</div>				
	
	
</div>
						
						<div class="section-method">
	<a name="//api/name/inDatabase:" title="inDatabase:"></a>
	<h3 class="subsubtitle method-title">inDatabase:</h3>
	
	
	<div class="method-subsection brief-description">
		<p>Synchronously perform database operations on queue.</p>
	</div>		
	
    
	<div class="method-subsection method-declaration"><code>- (void)inDatabase:(void ( ^ ) ( FMDatabase *db ))<em>block</em></code></div>

    
	<div class="method-subsection arguments-section parameters">
		<h4 class="method-subtitle parameter-title">Parameters</h4>
		
		<dl class="argument-def parameter-def">
			<dt><em>block</em></dt>
			<dd><p>The code to be run on the queue of <code>FMDatabaseQueue</code></p></dd>
		</dl>
		
	</div>
	
	
	<div class="method-subsection declared-in-section">
		<h4 class="method-subtitle">Declared In</h4>
		<code class="declared-in-ref">FMDatabaseQueue.h</code><br />
	</div>				
	
	
</div>
						
						<div class="section-method">
	<a name="//api/name/inDeferredTransaction:" title="inDeferredTransaction:"></a>
	<h3 class="subsubtitle method-title">inDeferredTransaction:</h3>
	
	
	<div class="method-subsection brief-description">
		<p>Synchronously perform database operations on queue, using deferred transactions.</p>
	</div>		
	
    
	<div class="method-subsection method-declaration"><code>- (void)inDeferredTransaction:(void ( ^ ) ( FMDatabase *db , BOOL *rollback ))<em>block</em></code></div>

    
	<div class="method-subsection arguments-section parameters">
		<h4 class="method-subtitle parameter-title">Parameters</h4>
		
		<dl class="argument-def parameter-def">
			<dt><em>block</em></dt>
			<dd><p>The code to be run on the queue of <code>FMDatabaseQueue</code></p></dd>
		</dl>
		
	</div>
	
	
	<div class="method-subsection declared-in-section">
		<h4 class="method-subtitle">Declared In</h4>
		<code class="declared-in-ref">FMDatabaseQueue.h</code><br />
	</div>				
	
	
</div>
						
						<div class="section-method">
	<a name="//api/name/inSavePoint:" title="inSavePoint:"></a>
	<h3 class="subsubtitle method-title">inSavePoint:</h3>
	
	
	<div class="method-subsection brief-description">
		<p>Synchronously perform database operations using save point.</p>
	</div>		
	
    
	<div class="method-subsection method-declaration"><code>- (NSError *)inSavePoint:(void ( ^ ) ( FMDatabase *db , BOOL *rollback ))<em>block</em></code></div>

    
	<div class="method-subsection arguments-section parameters">
		<h4 class="method-subtitle parameter-title">Parameters</h4>
		
		<dl class="argument-def parameter-def">
			<dt><em>block</em></dt>
			<dd><p>The code to be run on the queue of <code>FMDatabaseQueue</code></p></dd>
		</dl>
		
	</div>
	
	
	<div class="method-subsection declared-in-section">
		<h4 class="method-subtitle">Declared In</h4>
		<code class="declared-in-ref">FMDatabaseQueue.h</code><br />
	</div>				
	
	
</div>
						
						<div class="section-method">
	<a name="//api/name/inTransaction:" title="inTransaction:"></a>
	<h3 class="subsubtitle method-title">inTransaction:</h3>
	
	
	<div class="method-subsection brief-description">
		<p>Synchronously perform database operations on queue, using transactions.</p>
	</div>		
	
    
	<div class="method-subsection method-declaration"><code>- (void)inTransaction:(void ( ^ ) ( FMDatabase *db , BOOL *rollback ))<em>block</em></code></div>

    
	<div class="method-subsection arguments-section parameters">
		<h4 class="method-subtitle parameter-title">Parameters</h4>
		
		<dl class="argument-def parameter-def">
			<dt><em>block</em></dt>
			<dd><p>The code to be run on the queue of <code>FMDatabaseQueue</code></p></dd>
		</dl>
		
	</div>
	
	
	<div class="method-subsection declared-in-section">
		<h4 class="method-subtitle">Declared In</h4>
		<code class="declared-in-ref">FMDatabaseQueue.h</code><br />
	</div>				
	
	
</div>
						
						<div class="section-method">
	<a name="//api/name/initWithPath:" title="initWithPath:"></a>
	<h3 class="subsubtitle method-title">initWithPath:</h3>
	
	
	<div class="method-subsection brief-description">
		<p>Create queue using path.</p>
	</div>		
	
    
	<div class="method-subsection method-declaration"><code>- (instancetype)initWithPath:(NSString *)<em>aPath</em></code></div>

    
	<div class="method-subsection arguments-section parameters">
		<h4 class="method-subtitle parameter-title">Parameters</h4>
		
		<dl class="argument-def parameter-def">
			<dt><em>aPath</em></dt>
			<dd><p>The file path of the database.</p></dd>
		</dl>
		
	</div>
	
	
	<div class="method-subsection return">
		<h4 class="method-subtitle parameter-title">Return Value</h4>
		<p>The <code>FMDatabaseQueue</code> object. <code>nil</code> on error.</p>
	</div>
	
	
	<div class="method-subsection declared-in-section">
		<h4 class="method-subtitle">Declared In</h4>
		<code class="declared-in-ref">FMDatabaseQueue.h</code><br />
	</div>				
	
	
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