❌ Msg 8152 SQL Server Error: String or Binary Data Would Be Truncated

Introduction

While working with SQL Server, many developers face a very common yet confusing error:

String or binary data would be truncated

This error usually appears during INSERT or UPDATE operations and can be frustrating—especially in older SQL Server versions where the error does not clearly indicate which column caused the problem.

In this blog, we’ll understand:

What does this error mean
A real-world truncation scenario
Why it occurs
How to fix and prevent it

SQL Server Error Message Details

❌ Error Title (Official)

String or binary data would be truncated.

❌ Error Number

Msg 8152, Level 16, State 30

From SQL Server 2019 onward, the error message may also display the table name and column name, making debugging easier.

What Does This Error Mean?

This error occurs when you try to insert or update data that exceeds the maximum size defined for a column.

SQL Server does not automatically truncate data, because that could lead to data loss. Instead, it throws this error to protect data integrity.

Real-World Truncation Scenario

Step 1: Create a Table

CREATE TABLE Employee
(
    EmployeeID INT,
    EmployeeName VARCHAR(10)
);

Here, EmployeeName can store only 10 characters.

Step 2: Insert Valid Data

INSERT INTO Employee (EmployeeID, EmployeeName)
VALUES (1, 'Amit');

✅ Works fine.

Step 3: Insert Data That Causes Truncation

INSERT INTO Employee (EmployeeID, EmployeeName)
VALUES (2, 'MaheshKumar');

🚫 SQL Server throws:

Msg 8152, Level 16, State 30
String or binary data would be truncated.

Why Truncation Happens

Column size: VARCHAR(10)
Inserted value length: 11 characters
SQL Server prevents silent data loss
Operation fails with Msg 8152

Common Situations Where This Error Occurs

1️⃣ INSERT or UPDATE statements
2️⃣ Stored procedures receiving oversized parameters
3️⃣ Data migration between tables
4️⃣ SELECT INTO with incorrect column sizes
5️⃣ JSON, XML, or API data insertions

How to Identify the Exact Column (SQL Server 2019+)

SET ANSI_WARNINGS ON;

New detailed error message:

String or binary data would be truncated in table 'dbo.Employee',
column 'EmployeeName'.

✔️ This makes debugging much easier compared to older versions.

How to Fix the Error

✅ Solution 1: Increase Column Size

ALTER TABLE Employee
ALTER COLUMN EmployeeName VARCHAR(20);

✅ Solution 2: Truncate Data Explicitly (If Acceptable)

INSERT INTO Employee
VALUES (3, LEFT('MaheshKumar', 10));

⚠️ Use this only if data truncation is acceptable.

✅ Solution 3: Validate Data Before Insert

SELECT *
FROM EmployeeStaging
WHERE LEN(EmployeeName) > 10;

Best Practices to Avoid Truncation Errors

✔ Always validate data length before insert/update
✔ Match source and destination column sizes
✔ Be careful with VARCHAR, NVARCHAR, and JSON fields
✔ Log truncation errors during ETL or API imports

Conclusion

The “String or binary data would be truncated” error is SQL Server’s way of protecting your data from silent loss. Once you understand column sizes and input validation, fixing this error becomes straightforward.

Knowing why it happens helps you prevent it entirely.

Happy querying! 🚀