Text literals

Description

Use the text literal notation to specify values whenever string appears in the syntax of expressions, conditions, SQL functions, and SQL statements in other parts of this reference.

(Oracle SQL Language Reference Text literals)

[ {N | n} ]
{ '[ c ]...'
| { Q | q } 'quote_delimiter c [ c ]... quote_delimiter'
}

Sample Source Patterns

Empty string ('')

The empty strings are equivalent to NULL in Oracle, so in order to emulate the behavior in Snowflake, the empty strings are converted to NULL or undefined depending if the literal is used inside a procedure or not.

Oracle

Query

SELECT UPPER('') FROM DUAL;

Result

UPPER('')|
---------+
         |

Snowflake

Query

SELECT UPPER(NULL) FROM DUAL;

Result

UPPER(NULL)|
-----------+
           |

Empty string in stored procedures

Oracle

Query

CREATE TABLE empty_string_table(
col1 VARCHAR(10),
col2 VARCHAR(10));

CREATE OR REPLACE PROCEDURE null_proc AS
    var1 INTEGER := '';
    var3 INTEGER := null;
    var2 VARCHAR(20) := 'hello';
BEGIN
    var1 := var1 + 456;
    var2 := var2 || var1;
    IF var1 IS NULL THEN
        INSERT INTO empty_string_table VALUES (var1, var2);
    END IF;
END;

CALL null_proc();

SELECT * FROM empty_string_table;

Result

COL1	|COL2	|
--------+-------+
        |hello  |

Snowflake

Query

CREATE OR REPLACE TABLE PUBLIC.empty_string_table (
col1 VARCHAR(10),
col2 VARCHAR(10));

CREATE OR REPLACE PROCEDURE PUBLIC.null_proc ()
RETURNS STRING
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
   // REGION SnowConvert Helpers Code
   let VAR1 = undefined;
   let VAR3 = undefined;
   let VAR2 = `hello`;
   VAR1 = VAR1 + 456;
   // ** MSC-WARNING - MSCEWI1038 - THIS STATEMENT MAY BE A DYNAMIC SQL THAT COULD NOT BE RECOGNIZED AND CONVERTED **
   VAR2 = `${concatValue(VAR2)}${concatValue(VAR1)}`;
   if (IS_NULL(VAR1)) {
      EXEC(`INSERT INTO PUBLIC.empty_string_table VALUES (?, ?)`,[VAR1,VAR2]);
   }
$$;

CALL PUBLIC.null_proc();

SELECT * FROM PUBLIC.empty_string_table;

Result

COL1|COL2 |
----+-----+
    |hello|

Empty string in built-in functions

The transformation does not apply when the empty string is used as an argument of the REPLACE and CONCAT functions in order to keep the functional equivalence.

Oracle

Query

SELECT REPLACE('Hello world', '', 'l'), CONCAT('A','') FROM DUAL;

Result

REPLACE('HELLOWORLD','','L')|CONCAT('A','')|
----------------------------+--------------+
Hello world                 |A             |

Snowflake

Query

SELECT REPLACE('Hello world', '', 'l'), CONCAT('A','') FROM DUAL;

Result

REPLACE('HELLO WORLD', '', 'L')|CONCAT('A','')|
-------------------------------+--------------+
Hello world                    |A             |

If the empty strings are replaced by NULL for these cases, the results of the queries will be different.

Known Issues

No issues were found.

Related EWIs

1. MSCEWI1038: Dynamic SQL statement may be unrecognized.