Insert

Translation reference for SQL Server Insert statement to Snowflake

Applies to

• SQL Server

• Azure Synapse Analytics

Some parts in the output code are omitted for clarity reasons.

Description

Adds one or more rows to a table or a view in SQL Server. For more information regarding SQL Server Insert, check here.

Syntax comparison

The basic insert grammar is equivalent between both SQL languages. However there are still some other syntax elements in SQL Server that show differences, for example, one allows the developer to add a value to a column by using the assign operator. The syntax mentioned will be transformed to the basic insert syntax too.

For information about other special syntax elements in SQL Server like the ones shown in the below example please refer to the Known Issues section of this page.

Snowflake

INSERT [ OVERWRITE ] INTO <target_table> [ ( <target_col_name> [ , ... ] ) ]
       {
         VALUES ( { <value> | DEFAULT | NULL } [ , ... ] ) [ , ( ... ) ]  |
         <query>
       }

SQL Server

[ WITH <common_table_expression> [ ,...n ] ]  
INSERT   
{  
        [ TOP ( expression ) [ PERCENT ] ]   
        [ INTO ]   
        { <object> | rowset_function_limited   
          [ WITH ( <Table_Hint_Limited> [ ...n ] ) ]  
        }  
    {  
        [ ( column_list ) ]   
        [ <OUTPUT Clause> ]  
        { VALUES ( { DEFAULT | NULL | expression } [ ,...n ] ) [ ,...n     ]   
        | derived_table   
        | execute_statement  
        | <dml_table_source>  
        | DEFAULT VALUES   
        }  
    }  
}  
[;]  
  
<object> ::=  
{   
    [ server_name . database_name . schema_name .   
      | database_name .[ schema_name ] .   
      | schema_name .   
    ]  
  table_or_view_name  
}  
  
<dml_table_source> ::=  
    SELECT <select_list>  
    FROM ( <dml_statement_with_output_clause> )   
      [AS] table_alias [ ( column_alias [ ,...n ] ) ]  
    [ WHERE <search_condition> ]  
        [ OPTION ( <query_hint> [ ,...n ] ) ] 

Sample Source Patterns

Basic INSERT

SQL Server

IN -> SqlServer_01.sql

INSERT INTO TABLE1 VALUES (1, 2, 123, 'LiteralValue');

Snowflake

OUT -> SqlServer_01.sql

INSERT INTO TABLE1 VALUES (1, 2, 123, 'LiteralValue');

INSERT with assing operator

SQL Server

IN -> SqlServer_02.sql

INSERT INTO aTable (columnA = 'varcharValue', columnB = 1);

Snowflake

OUT -> SqlServer_02.sql

INSERT INTO aTable (columnA = 'varcharValue', columnB = 1);

INSERT with no INTO

SQL Server

IN -> SqlServer_03.sql

INSERT exampleTable VALUES ('Hello', 23);

Snowflake

OUT -> SqlServer_03.sql

INSERT INTO exampleTable VALUES ('Hello', 23);

INSERT with common table expression

SQL Server

IN -> SqlServer_04.sql

WITH ctevalues (textCol, numCol) AS (SELECT 'cte string', 155)
INSERT INTO exampleTable SELECT * FROM ctevalues;

Snowflake

OUT -> SqlServer_04.sql

INSERT INTO exampleTable
WITH ctevalues (
textCol,
numCol
) AS (SELECT 'cte string', 155)
SELECT
*
FROM
ctevalues AS ctevalues;

INSERT with Table DML Factor with MERGE as DML

This case is so specific where the INSERT statement has a SELECT query, and the FROM clause of the SELECT mentioned contains a MERGE DML statement. Looking for an equivalent in Snowflake, the next statements are created: a temporary table, the merge statement converted, and finally, the insert statement.

SQL Server

IN -> SqlServer_05.sql

INSERT INTO T3
SELECT
  col1,
  col2
FROM (
  MERGE T1 USING T2
  	ON T1.col1 = T2.col1
  WHEN NOT MATCHED THEN
    INSERT VALUES ( T2.col1, T2.col2 )
  WHEN MATCHED THEN
    UPDATE SET T1.col2 = t2.col2
  OUTPUT
  	$action ACTION_OUT,
    T2.col1,
    T2.col2
) AS MERGE_OUT
 WHERE ACTION_OUT='UPDATE';

Snowflake

OUT-> SqlServer_05.sql

--** SSC-FDM-TS0026 - DELETE CASE IS NOT BEING CONSIDERED, PLEASE CHECK IF THE ORIGINAL MERGE PERFORMS IT **
CREATE OR REPLACE TEMPORARY TABLE MERGE_OUT AS
SELECT
	CASE WHEN T1.$1 IS NULL THEN 'INSERT' ELSE 'UPDATE' END ACTION_OUT,
	T2.col1,
	T2.col2
FROM T2 LEFT JOIN T1 ON T1.col1 = T2.col1;

MERGE INTO T1
USING T2
ON T1.col1 = T2.col1
WHEN NOT MATCHED THEN INSERT VALUES (T2.col1, T2.col2)
WHEN MATCHED THEN UPDATE SET T1.col2 = t2.col2
!!!RESOLVE EWI!!! /*** SSC-EWI-0021 - OUTPUT CLAUSE NOT SUPPORTED IN SNOWFLAKE ***/!!!
OUTPUT
	$action ACTION_OUT,
	T2.col1,
	T2.col2 ;

INSERT INTO T3
SELECT col1, col2
FROM MERGE_OUT
WHERE ACTION_OUT ='UPDATE';

NOTE: As the pattern's name suggests, it is ONLY for cases where the insert comes with a select...from which the body contains a MERGE statement.

Known Issues

1. Syntax elements that require special mappings:

• [INTO]: This keyword is obligatory in Snowflake and should be added if not present.

• [DEFAULT VALUES]: Inserts the default value in all columns specified in the insert. Should be transformed to VALUES (DEFAULT, DEFAULT, ...), the amount of DEFAULTs added equals the number of columns the insert will modify. For now, there is a warning being added.

  SQL Server

IN -> SqlServer_05.sql

INSERT INTO exampleTable DEFAULT VALUES;

#### Snowflake

OUT -> SqlServer_05.sql

!!!RESOLVE EWI!!! /*** SSC-EWI-0073 - PENDING FUNCTIONAL EQUIVALENCE REVIEW FOR 'INSERT WITH DEFAULT VALUES' NODE ***/!!!
INSERT INTO exampleTable DEFAULT VALUES;

2. Syntax elements not supported or irrelevant:

• [TOP (expression) [PERCENT]]: Indicates the amount or percent of rows that will be inserted. Not supported.

• [rowset_function_limited]: It is either OPENQUERY() or OPENROWSET(), used to read data from remote servers. Not supported.

• [WITH table_hint_limited]: These are used to get reading/writing locks on tables. Not relevant in Snowflake.

• [<OUTPUT Clause>]: Specifies a table or result set in which the inserted rows will also be inserted. Not supported.

• [execute_statement]: Can be used to run a query to get data from. Not supported.

• [dml_table_source]: A temporary result set generated by the OUTPUT clause of another DML statement. Not supported.

3. The DELETE case is not being considered.

• For the INSERT with Table DML Factor with MERGE as DML pattern, the DELETE case is not being considered in the solution, so if the source code merge statement has a DELETE case please consider that it might not work as expected.

Related EWIs

1. SSC-EWI-0073: Pending Functional Equivalence Review.

2. SSC-FDM-TS0026: DELETE case is not being considered.