Using _ for Single Character Matching in SFMC SQL LIKE Operator

 🔹 The _ wildcard in SFMC SQL matches exactly ONE character.

• Unlike %, which matches multiple characters, _ only replaces a single character.

• It’s useful when you need to find values of a fixed format or specific character positions.

1. _ in Fixed-Length Patterns: _ ensures only one character is replaced at a time.

Since my Source DE did not have two character I used 4 character (Pune: P___)

2. _ in Email Pattern Matching: You can use _ to detect formatting errors in emails.

• '_____%@%' → Matches emails where the username has exactly 5 characters before @.

• %@% ensures that "@" appears somewhere in the email.

Question: When I use this filter, it takes all the email address from the source DE so is it not working?

If I use __@gmail.com, it takes only the @gmail.com to target DE but the _ does not define the number of letters before @

3. _ in Phone Number Validation

• '___-___-____' → Ensures that the phone number follows the exact format of 3-3-4 digits.

• It excludes numbers that are too short, too long, or missing dashes.

Since the Phone number stored in my Source DE was in format __________ it did not work when i used the format ___-___-____. So the format I use in the Automation filter should match my source DE for it to appear in target DE

Incorrect Format as per my Source DE:

Added with correct Format:

4. _ in Product Code Matching

• 'A___' → Matches values that start with "A" followed by exactly three characters.

• It excludes A98 (too short) and A1X3 (includes a letter in place of a number).

_ is helpful when product codes follow a fixed structure. (Need to be followed in the same format as source DE. For example if my source DE has a Properties named "ABC DEF", I have to enter the underscore in the same format; '___ ___' and if its ABCDE it should be '_____'. Same number of underscore and same amount of spaces.