---
title: "ISJSON (Transact-SQL) | Microsoft Docs"
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  - "ISJSON function"
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---
# ISJSON (Transact-SQL)
[!INCLUDE[tsql-appliesto-ss2016-asdb-xxxx-xxx_md](../../includes/tsql-appliesto-ss2016-asdb-xxxx-xxx-md.md)]

  Tests whether a string contains valid JSON.  
  
 ![Topic link icon](../../database-engine/configure-windows/media/topic-link.gif "Topic link icon") [Transact-SQL Syntax Conventions](../../t-sql/language-elements/transact-sql-syntax-conventions-transact-sql.md)  
  
## Syntax  
  
```sql  
ISJSON ( expression )  
```  
  
## Arguments  
 *expression*  
 The string to test.  
  
## Return Value  
 Returns 1 if the string contains valid JSON; otherwise, returns 0. Returns null if *expression* is null.  
  
 Does not return errors.  
  
## Remarks  
 **ISJSON** does not check the uniqueness of keys at the same level.  
  
## Examples  
  
### Example 1  
The following example runs a statement block conditionally if the parameter value `@param` contains valid JSON.  
  
```sql  
DECLARE @param <data type>
SET @param = <value>

IF (ISJSON(@param) > 0)  
BEGIN  
     -- Do something with the valid JSON value of @param.  
END
 
```  
  
### Example 2  
The following example returns rows in which the column `json_col` contains valid JSON.  
  
```sql  
SELECT id, json_col
FROM tab1
WHERE ISJSON(json_col) > 0 
```  
  
## See Also  
 [JSON Data &#40;SQL Server&#41;](../../relational-databases/json/json-data-sql-server.md)