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SQL Interview Success: Unlocking the Top 5 Frequently Asked Queries

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 Here are the five top commonly asked SQL queries in the interviews. These you can expect in Data Analyst, or, Data Engineer interviews. Top SQL Queries for Interviews 01. Joins The commonly asked question pertains to providing two tables, determining the number of rows that will return on various join types, and the resultant. Table1 -------- id ---- 1 1 2 3 Table2 -------- id ---- 1 3 1 NULL Output ------- Inner join --------------- 5 rows will return The result will be: =============== 1  1 1   1 1   1 1    1 3    3 02. Substring and Concat Here, we need to write an SQL query to make the upper case of the first letter and the small case of the remaining letter. Table1 ------ ename ===== raJu venKat kRIshna Solution: ========== SELECT CONCAT(UPPER(SUBSTRING(name, 1, 1)), LOWER(SUBSTRING(name, 2))) AS capitalized_name FROM Table1; 03. Case statement SQL Query ========= SELECT Code1, Code2,      CASE         WHEN Code1 = 'A' AND Code2 = 'AA' THEN "A" | "A

3 SQL Query Examples to Create Views Quickly

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There are three kinds of Views in SQL. The three views are Read-only, Force, and Updatable. Views real usage is to hide data. And you need to ensure base tables are present before you create a View. You can call views as logical tables. The advantage of Views is you can show only some of the fields of base tables. What is a View in SQL A view can be constructed with another view so it is called a nested view. You can create or replace an existing view A view can be created without having base tables. This is possible with the FORCE option. #1: Read-Only Views The standard syntax for the view is as follows: CREATE OR replace VIEW invoice_summary AS SELECT vendor_name count(*) AS invoice_count, SUM(invoice_total) AS invoice_total_sum FROM vendor JOIN invoices ON vendors.vendor_id*invoices.vendor_id GROUP BY vendor_name; Notes: You cannot update Read-only Views #2: Force Views CREATE FORCE VIEW products_list AS SELECT product_description, product_price FROM products;