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new 02a07cd6adc [SPARK-43205][DOC] identifier clause docs
02a07cd6adc is described below
commit 02a07cd6adc7f0674bc673e3f917d71d9b290199
Author: srielau <se...@rielau.com>
AuthorDate: Fri Aug 18 09:26:32 2023 +0800
[SPARK-43205][DOC] identifier clause docs
### What changes were proposed in this pull request?
Document the IDENTIFIER() clause
### Why are the changes needed?
Docs are good!
### Does this PR introduce _any_ user-facing change?
### How was this patch tested?
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See attached
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Closes #42506 from srielau/SPARK-43205-3.5-IDENTIFIER-clause-docs.
Authored-by: srielau <se...@rielau.com>
Signed-off-by: Wenchen Fan <wenc...@databricks.com>
(cherry picked from commit 7786d0b2f359eccd570461a399da0fca84e515c1)
Signed-off-by: Wenchen Fan <wenc...@databricks.com>
---
docs/sql-ref-identifier-clause.md | 106 ++++++++++++++++++++++++++++++++++++++
docs/sql-ref.md | 1 +
2 files changed, 107 insertions(+)
diff --git a/docs/sql-ref-identifier-clause.md
b/docs/sql-ref-identifier-clause.md
new file mode 100644
index 00000000000..694731109f8
--- /dev/null
+++ b/docs/sql-ref-identifier-clause.md
@@ -0,0 +1,106 @@
+---
+layout: global
+title: Identifier clause
+displayTitle: IDENTIFIER clause
+license: |
+ Licensed to the Apache Software Foundation (ASF) under one or more
+ contributor license agreements. See the NOTICE file distributed with
+ this work for additional information regarding copyright ownership.
+ The ASF licenses this file to You under the Apache License, Version 2.0
+ (the "License"); you may not use this file except in compliance with
+ the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+---
+
+### Description
+
+Converts a constant `STRING` 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 as argument.
+
+### Syntax
+
+```sql
+IDENTIFIER ( strExpr )
+```
+
+### Parameters
+
+- **strExpr**: A constant `STRING` expression. Typically, the expression
includes a parameter marker.
+
+### Returns
+
+A (qualified) identifier which can be used as a:
+
+- qualified table name
+- namespace name
+- function name
+- qualified column or attribute reference
+
+### Examples
+
+These examples use named parameter markers to templatize queries.
+
+```scala
+// Creation of a table using parameter marker.
+spark.sql("CREATE TABLE IDENTIFIER(:mytab)(c1 INT)", args = Map("mytab" ->
"tab1")).show()
+
+spark.sql("DESCRIBE IDENTIFIER(:mytab)", args = Map("mytab" -> "tab1")).show()
++--------+---------+-------+
+|col_name|data_type|comment|
++--------+---------+-------+
+| c1| int| NULL|
++--------+---------+-------+
+
+// Altering a table with a fixed schema and a parameterized table name.
+spark.sql("ALTER TABLE IDENTIFIER('default.' || :mytab) ADD COLUMN c2 INT",
args = Map("mytab" -> "tab1")).show()
+
+spark.sql("DESCRIBE IDENTIFIER(:mytab)", args = Map("mytab" ->
"default.tab1")).show()
++--------+---------+-------+
+|col_name|data_type|comment|
++--------+---------+-------+
+| c1| int| NULL|
+| c2| int| NULL|
++--------+---------+-------+
+
+// A parameterized reference to a table in a query. This table name is
qualified and uses back-ticks.
+spark.sql("SELECT * FROM IDENTIFIER(:mytab)", args = Map("mytab" ->
"`default`.`tab1`")).show()
++---+---+
+| c1| c2|
++---+---+
++---+---+
+
+
+// You cannot qualify the IDENTIFIER clause or use it as a qualifier itself.
+spark.sql("SELECT * FROM myschema.IDENTIFIER(:mytab)", args = Map("mytab" ->
"`tab1`")).show()
+[INVALID_SQL_SYNTAX.INVALID_TABLE_VALUED_FUNC_NAME] `myschema`.`IDENTIFIER`.
+
+spark.sql("SELECT * FROM IDENTIFIER(:myschema).mytab", args = Map("mychema" ->
"`default`")).show()
+[PARSE_SYNTAX_ERROR]
+
+// Dropping a table with separate schema and table parameters.
+spark.sql("DROP TABLE IDENTIFIER(:myschema || '.' || :mytab)", args =
Map("myschema" -> "default", "mytab" -> "tab1")).show()
+
+// A parameterized column reference
+spark.sql("SELECT IDENTIFIER(:col) FROM VALUES(1) AS T(c1)", args = Map("col"
-> "t.c1")).show()
++---+
+| c1|
++---+
+| 1|
++---+
+
+// Passing in a function name as a parameter
+spark.sql("SELECT IDENTIFIER(:func)(-1)", args = Map("func" -> "abs")).show();
++-------+
+|abs(-1)|
++-------+
+| 1|
++-------+
+```
diff --git a/docs/sql-ref.md b/docs/sql-ref.md
index 026d072c07d..8f3289e9b77 100644
--- a/docs/sql-ref.md
+++ b/docs/sql-ref.md
@@ -32,6 +32,7 @@ Spark SQL is Apache Spark's module for working with
structured data. This guide
* [User-Defined Aggregate Functions
(UDAFs)](sql-ref-functions-udf-aggregate.html)
* [Integration with Hive UDFs/UDAFs/UDTFs](sql-ref-functions-udf-hive.html)
* [Identifiers](sql-ref-identifier.html)
+ * [IDENTIFIER clause](sql-ref-identifier-clause.html)
* [Literals](sql-ref-literals.html)
* [Null Semantics](sql-ref-null-semantics.html)
* [SQL Syntax](sql-ref-syntax.html)
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