Added sql-data-types.md in SQL under docs

docs/DBMS/Structured Query Language/sql-data-types.md

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+---
+id: sql-data-types
+title: DBMS - SQL data-types
+sidebar_label: Data-Types
+sidebar_position: 5
+description: SQL data-types
+tags:
+  - DBMS
+  - SQL
+  - Data Types
+---
+
+## Introduction:
+Varios datatypes are supported in SQL. They include numeric data types, string data types and date and time.
+
+## Numeric data types
+
+1. int- <br /> For integer data.
+eg:
+```sql
+create table temp(
+ age int
+);
+```
+2. tinyint- <br />For very small values.
+3. smallint- <br />For small values.
+4. mediumint- <br /> For medium vakues.
+5. bigint- <br /> Upto 20 digits.
+6. float- <br /> Used for decimals. It has 2 arguments, length and the number of digits after decimals.
+eg:
+```sql
+create table temp(
+    cash float(10,2)
+);
+```
+7. double- <br /> Similar to float but can denote much larger numbers.
+
+
+## String data types
+
+1. char- <br /> Used if the length of string is fixed. Has an argument, the length.
+2. varchar- <br /> Used for variable length strings. It also has an argument, the maximum possible length.
+eg:
+```sql
+create table temp(
+ name varchar(50)
+);
+```
+
+## Date and Time
+
+1. date
+2. time
+3. datetime
+4. timestamnp