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| IDENTIFIER clause |
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| <h1 class="title">IDENTIFIER clause</h1> |
| |
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| <h3 id="description">Description</h3> |
| |
| <p>Converts a constant <code class="language-plaintext highlighter-rouge">STRING</code> expression into a SQL object name. |
| The purpose of this clause is to allow for templating of identifiers in SQL statements without opening up the risk of SQL injection attacks. |
| Typically, this clause is used with a parameter marker or a variable as argument.</p> |
| |
| <h3 id="syntax">Syntax</h3> |
| |
| <div class="language-sql highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="n">IDENTIFIER</span> <span class="p">(</span> <span class="n">strExpr</span> <span class="p">)</span> |
| </code></pre></div></div> |
| |
| <h3 id="parameters">Parameters</h3> |
| |
| <ul> |
| <li><strong>strExpr</strong>: A constant <code class="language-plaintext highlighter-rouge">STRING</code> expression. Typically, the expression includes a parameter marker.</li> |
| </ul> |
| |
| <h3 id="returns">Returns</h3> |
| |
| <p>A (qualified) identifier which can be used as a:</p> |
| |
| <ul> |
| <li>qualified table name</li> |
| <li>namespace name</li> |
| <li>function name</li> |
| <li>qualified column or attribute reference</li> |
| </ul> |
| |
| <h3 id="examples">Examples</h3> |
| |
| <h4 id="scala-examples">Scala examples</h4> |
| |
| <p>These examples use named parameter markers to templatize queries.</p> |
| |
| <div class="language-scala highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="c1">// Creation of a table using parameter marker.</span> |
| <span class="nv">spark</span><span class="o">.</span><span class="py">sql</span><span class="o">(</span><span class="s">"CREATE TABLE IDENTIFIER(:mytab)(c1 INT)"</span><span class="o">,</span> <span class="n">args</span> <span class="k">=</span> <span class="nc">Map</span><span class="o">(</span><span class="s">"mytab"</span> <span class="o">-></span> <span class="s">"tab1"</span><span class="o">)).</span><span class="py">show</span><span class="o">()</span> |
| |
| <span class="nv">spark</span><span class="o">.</span><span class="py">sql</span><span class="o">(</span><span class="s">"DESCRIBE IDENTIFIER(:mytab)"</span><span class="o">,</span> <span class="n">args</span> <span class="k">=</span> <span class="nc">Map</span><span class="o">(</span><span class="s">"mytab"</span> <span class="o">-></span> <span class="s">"tab1"</span><span class="o">)).</span><span class="py">show</span><span class="o">()</span> |
| <span class="o">+--------+---------+-------+</span> |
| <span class="o">|</span><span class="n">col_name</span><span class="o">|</span><span class="n">data_type</span><span class="o">|</span><span class="n">comment</span><span class="o">|</span> |
| <span class="o">+--------+---------+-------+</span> |
| <span class="o">|</span> <span class="n">c1</span><span class="o">|</span> <span class="n">int</span><span class="o">|</span> <span class="nc">NULL</span><span class="o">|</span> |
| <span class="o">+--------+---------+-------+</span> |
| |
| <span class="c1">// Altering a table with a fixed schema and a parameterized table name. </span> |
| <span class="nv">spark</span><span class="o">.</span><span class="py">sql</span><span class="o">(</span><span class="s">"ALTER TABLE IDENTIFIER('default.' || :mytab) ADD COLUMN c2 INT"</span><span class="o">,</span> <span class="n">args</span> <span class="k">=</span> <span class="nc">Map</span><span class="o">(</span><span class="s">"mytab"</span> <span class="o">-></span> <span class="s">"tab1"</span><span class="o">)).</span><span class="py">show</span><span class="o">()</span> |
| |
| <span class="nv">spark</span><span class="o">.</span><span class="py">sql</span><span class="o">(</span><span class="s">"DESCRIBE IDENTIFIER(:mytab)"</span><span class="o">,</span> <span class="n">args</span> <span class="k">=</span> <span class="nc">Map</span><span class="o">(</span><span class="s">"mytab"</span> <span class="o">-></span> <span class="s">"default.tab1"</span><span class="o">)).</span><span class="py">show</span><span class="o">()</span> |
| <span class="o">+--------+---------+-------+</span> |
| <span class="o">|</span><span class="n">col_name</span><span class="o">|</span><span class="n">data_type</span><span class="o">|</span><span class="n">comment</span><span class="o">|</span> |
| <span class="o">+--------+---------+-------+</span> |
| <span class="o">|</span> <span class="n">c1</span><span class="o">|</span> <span class="n">int</span><span class="o">|</span> <span class="nc">NULL</span><span class="o">|</span> |
| <span class="o">|</span> <span class="n">c2</span><span class="o">|</span> <span class="n">int</span><span class="o">|</span> <span class="nc">NULL</span><span class="o">|</span> |
| <span class="o">+--------+---------+-------+</span> |
| |
| <span class="c1">// A parameterized reference to a table in a query. This table name is qualified and uses back-ticks.</span> |
| <span class="nv">spark</span><span class="o">.</span><span class="py">sql</span><span class="o">(</span><span class="s">"SELECT * FROM IDENTIFIER(:mytab)"</span><span class="o">,</span> <span class="n">args</span> <span class="k">=</span> <span class="nc">Map</span><span class="o">(</span><span class="s">"mytab"</span> <span class="o">-></span> <span class="s">"`default`.`tab1`"</span><span class="o">)).</span><span class="py">show</span><span class="o">()</span> |
| <span class="o">+---+---+</span> |
| <span class="o">|</span> <span class="n">c1</span><span class="o">|</span> <span class="n">c2</span><span class="o">|</span> |
| <span class="o">+---+---+</span> |
| <span class="o">+---+---+</span> |
| |
| |
| <span class="c1">// You cannot qualify the IDENTIFIER clause or use it as a qualifier itself.</span> |
| <span class="nv">spark</span><span class="o">.</span><span class="py">sql</span><span class="o">(</span><span class="s">"SELECT * FROM myschema.IDENTIFIER(:mytab)"</span><span class="o">,</span> <span class="n">args</span> <span class="k">=</span> <span class="nc">Map</span><span class="o">(</span><span class="s">"mytab"</span> <span class="o">-></span> <span class="s">"`tab1`"</span><span class="o">)).</span><span class="py">show</span><span class="o">()</span> |
| <span class="o">[</span><span class="kt">INVALID_SQL_SYNTAX.INVALID_TABLE_VALUED_FUNC_NAME</span><span class="o">]</span> <span class="n">`myschema`</span><span class="o">.</span><span class="n">`IDENTIFIER`</span><span class="o">.</span> |
| |
| <span class="nv">spark</span><span class="o">.</span><span class="py">sql</span><span class="o">(</span><span class="s">"SELECT * FROM IDENTIFIER(:myschema).mytab"</span><span class="o">,</span> <span class="n">args</span> <span class="k">=</span> <span class="nc">Map</span><span class="o">(</span><span class="s">"mychema"</span> <span class="o">-></span> <span class="s">"`default`"</span><span class="o">)).</span><span class="py">show</span><span class="o">()</span> |
| <span class="o">[</span><span class="kt">PARSE_SYNTAX_ERROR</span><span class="o">]</span> |
| |
| <span class="c1">// Dropping a table with separate schema and table parameters.</span> |
| <span class="nv">spark</span><span class="o">.</span><span class="py">sql</span><span class="o">(</span><span class="s">"DROP TABLE IDENTIFIER(:myschema || '.' || :mytab)"</span><span class="o">,</span> <span class="n">args</span> <span class="k">=</span> <span class="nc">Map</span><span class="o">(</span><span class="s">"myschema"</span> <span class="o">-></span> <span class="s">"default"</span><span class="o">,</span> <span class="s">"mytab"</span> <span class="o">-></span> <span class="s">"tab1"</span><span class="o">)).</span><span class="py">show</span><span class="o">()</span> |
| |
| <span class="c1">// A parameterized column reference</span> |
| <span class="nv">spark</span><span class="o">.</span><span class="py">sql</span><span class="o">(</span><span class="s">"SELECT IDENTIFIER(:col) FROM VALUES(1) AS T(c1)"</span><span class="o">,</span> <span class="n">args</span> <span class="k">=</span> <span class="nc">Map</span><span class="o">(</span><span class="s">"col"</span> <span class="o">-></span> <span class="s">"t.c1"</span><span class="o">)).</span><span class="py">show</span><span class="o">()</span> |
| <span class="o">+---+</span> |
| <span class="o">|</span> <span class="n">c1</span><span class="o">|</span> |
| <span class="o">+---+</span> |
| <span class="o">|</span> <span class="mi">1</span><span class="o">|</span> |
| <span class="o">+---+</span> |
| |
| <span class="c1">// Passing in a function name as a parameter</span> |
| <span class="nv">spark</span><span class="o">.</span><span class="py">sql</span><span class="o">(</span><span class="s">"SELECT IDENTIFIER(:func)(-1)"</span><span class="o">,</span> <span class="n">args</span> <span class="k">=</span> <span class="nc">Map</span><span class="o">(</span><span class="s">"func"</span> <span class="o">-></span> <span class="s">"abs"</span><span class="o">)).</span><span class="py">show</span><span class="o">();</span> |
| <span class="o">+-------+</span> |
| <span class="o">|</span><span class="nf">abs</span><span class="o">(-</span><span class="mi">1</span><span class="o">)|</span> |
| <span class="o">+-------+</span> |
| <span class="o">|</span> <span class="mi">1</span><span class="o">|</span> |
| <span class="o">+-------+</span> |
| </code></pre></div></div> |
| |
| <h4 id="sql-examples">SQL examples</h4> |
| |
| <p>These examples use SQL variables to templatize queries.</p> |
| |
| <div class="language-sql highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="k">DECLARE</span> <span class="n">mytab</span> <span class="o">=</span> <span class="s1">'tab1'</span><span class="p">;</span> |
| |
| <span class="c1">-- Creation of a table using variable.</span> |
| <span class="k">CREATE</span> <span class="k">TABLE</span> <span class="n">IDENTIFIER</span><span class="p">(</span><span class="n">mytab</span><span class="p">)(</span><span class="n">c1</span> <span class="nb">INT</span><span class="p">);</span> |
| |
| <span class="k">DESCRIBE</span> <span class="n">IDENTIFIER</span><span class="p">(</span><span class="n">mytab</span><span class="p">);</span> |
| <span class="o">+</span><span class="c1">--------+---------+-------+</span> |
| <span class="o">|</span><span class="n">col_name</span><span class="o">|</span><span class="n">data_type</span><span class="o">|</span><span class="k">comment</span><span class="o">|</span> |
| <span class="o">+</span><span class="c1">--------+---------+-------+</span> |
| <span class="o">|</span> <span class="n">c1</span><span class="o">|</span> <span class="nb">int</span><span class="o">|</span> <span class="k">NULL</span><span class="o">|</span> |
| <span class="o">+</span><span class="c1">--------+---------+-------+</span> |
| |
| <span class="c1">-- Altering a table with a fixed schema and a parameterized table name. </span> |
| <span class="k">ALTER</span> <span class="k">TABLE</span> <span class="n">IDENTIFIER</span><span class="p">(</span><span class="s1">'default.'</span> <span class="o">||</span> <span class="n">mytab</span><span class="p">)</span> <span class="k">ADD</span> <span class="k">COLUMN</span> <span class="n">c2</span> <span class="nb">INT</span><span class="p">;</span> |
| |
| <span class="k">SET</span> <span class="n">VAR</span> <span class="n">mytab</span> <span class="o">=</span> <span class="s1">'`default`.`tab1`'</span><span class="p">;</span> |
| <span class="k">DESCRIBE</span> <span class="n">IDENTIFIER</span><span class="p">(</span><span class="n">mytab</span><span class="p">);</span> |
| <span class="o">+</span><span class="c1">--------+---------+-------+</span> |
| <span class="o">|</span><span class="n">col_name</span><span class="o">|</span><span class="n">data_type</span><span class="o">|</span><span class="k">comment</span><span class="o">|</span> |
| <span class="o">+</span><span class="c1">--------+---------+-------+</span> |
| <span class="o">|</span> <span class="n">c1</span><span class="o">|</span> <span class="nb">int</span><span class="o">|</span> <span class="k">NULL</span><span class="o">|</span> |
| <span class="o">|</span> <span class="n">c2</span><span class="o">|</span> <span class="nb">int</span><span class="o">|</span> <span class="k">NULL</span><span class="o">|</span> |
| <span class="o">+</span><span class="c1">--------+---------+-------+</span> |
| |
| <span class="c1">-- A parameterized reference to a table in a query. This table name is qualified and uses back-ticks.</span> |
| <span class="k">SELECT</span> <span class="o">*</span> <span class="k">FROM</span> <span class="n">IDENTIFIER</span><span class="p">(</span><span class="n">mytab</span><span class="p">);</span> |
| <span class="o">+</span><span class="c1">---+---+</span> |
| <span class="o">|</span> <span class="n">c1</span><span class="o">|</span> <span class="n">c2</span><span class="o">|</span> |
| <span class="o">+</span><span class="c1">---+---+</span> |
| <span class="o">+</span><span class="c1">---+---+</span> |
| |
| |
| <span class="c1">-- Dropping a table with separate schema and table parameters.</span> |
| <span class="k">DECLARE</span> <span class="n">myschema</span> <span class="o">=</span> <span class="s1">'default'</span><span class="p">;</span> |
| <span class="k">SET</span> <span class="n">VAR</span> <span class="n">mytab</span> <span class="o">=</span> <span class="s1">'tab1'</span><span class="p">;</span> |
| <span class="k">DROP</span> <span class="k">TABLE</span> <span class="n">IDENTIFIER</span><span class="p">(</span><span class="n">myschema</span> <span class="o">||</span> <span class="s1">'.'</span> <span class="o">||</span> <span class="n">mytab</span><span class="p">);</span> |
| |
| <span class="c1">-- A parameterized column reference</span> |
| <span class="k">DECLARE</span> <span class="n">col</span> <span class="o">=</span> <span class="s1">'t.c1'</span><span class="p">;</span> |
| <span class="k">SELECT</span> <span class="n">IDENTIFIER</span><span class="p">(</span><span class="n">col</span><span class="p">)</span> <span class="k">FROM</span> <span class="k">VALUES</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span> <span class="k">AS</span> <span class="n">T</span><span class="p">(</span><span class="n">c1</span><span class="p">);</span> |
| <span class="o">+</span><span class="c1">---+</span> |
| <span class="o">|</span> <span class="n">c1</span><span class="o">|</span> |
| <span class="o">+</span><span class="c1">---+</span> |
| <span class="o">|</span> <span class="mi">1</span><span class="o">|</span> |
| <span class="o">+</span><span class="c1">---+</span> |
| |
| <span class="c1">-- Passing in a function name as a parameter</span> |
| <span class="k">DECLARE</span> <span class="n">func</span> <span class="o">=</span> <span class="s1">'abs'</span><span class="p">;</span> |
| <span class="k">SELECT</span> <span class="n">IDENTIFIER</span><span class="p">(</span><span class="n">func</span><span class="p">)(</span><span class="o">-</span><span class="mi">1</span><span class="p">);</span> |
| <span class="o">+</span><span class="c1">-------+</span> |
| <span class="o">|</span><span class="k">abs</span><span class="p">(</span><span class="o">-</span><span class="mi">1</span><span class="p">)</span><span class="o">|</span> |
| <span class="o">+</span><span class="c1">-------+</span> |
| <span class="o">|</span> <span class="mi">1</span><span class="o">|</span> |
| <span class="o">+</span><span class="c1">-------+</span> |
| </code></pre></div></div> |
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