syntax links

Author: XiaoyuMSFT

articles/synapse-analytics/sql-data-warehouse/sql-data-warehouse-table-constraints.md

@@ -23,8 +23,11 @@ Synapse SQL pool supports these table constraints:
 - PRIMARY KEY is only supported when NONCLUSTERED and NOT ENFORCED are both used.    
 - UNIQUE constraint is only supported with NOT ENFORCED is used.
 
+For syntax, check [ALTER TABLE](https://docs.microsoft.com/sql/t-sql/statements/alter-table-transact-sql) and [CREATE TABLE](https://docs.microsoft.com/sql/t-sql/statements/create-table-azure-sql-data-warehouse). 
+
 FOREIGN KEY constraint is not supported in Synapse SQL pool.  
 
+
 ## Remarks
 
 Having primary key and/or unique key allows Synapse SQL pool engine to generate an optimal execution plan for a query.  All values in a primary key column or a unique constraint column should be unique.