sqlExam1Review.ppt EXAM - 1

SQL stands for -- Structured Query Language Putting a manual database on a computer ensures? Data is more current Data is more accurate You can generate useful reports Timely & Accurate

Relational DBMS provides? - Ask questions of the database - Retrieve information from the database quickly - Find the answer to a question easily Before storing data in a database, you should know? Know what information you will maintain in the database The most basic form of an SQL statement is? SELECT FROMSELECT FROM WHERE

Each table in your database will normally have a(n) ____________ that uniquely identifies each _____________. Primary KeyRow/Record FACT!! Relational DBMS allows you to retrieve information from the database quickly!!! The phase that is needed in the SELECT command to restrict to picking particular rows? WHERE

You list the name of the table that contains the data to retrieve in the _________________ clause of the SELECT command. FROM Another name for AND, OR? BOOLEAN The =, >, are what type of operators? Relational Rapid system development process is also defined as? Prototyping Comparison operators

Operations for manipulating relations 1. Product 2. Union 3. Intersect (ion) 4. Difference Commutative Operations We match every row of relation A with every row of relation B Join all rows in both relations, removing duplicates Including only the rows that match your where clause Including only rows that do not match -- select all rows from first table that are NOT in the second table

II. Relational Algebra - continued C. Operations for manipulating relations 5. Selection 6. Projection 7. Join 8. Assignment Select only specific attributes (columns) Selects specific rows based on data values Using operators (=, >, etc..) to combine data from two or more relations Assign a new name to relations that are created as a result of a join, projection, selection, etc.

If you want to select all rows from a table, you do not need to use a ____________ in your SELECT command. WHERE If you want to select all columns from a table, you need to use a ____________ in your SELECT command. * WHERE SLSREP_NUMBER = '06' is an example of a _______________ condition. SIMPLE Wild card symbols that we have used are? * -- selects ALLcolumns % -- group of characters can be placed at the beginning or end of character (Used with the LIKE clause) _ -- represents any individual character

LIKE ?? -- operator lets you test a string value to see whether it contains certain characters The ___________ clause is used to sort output in a specific order. Order By IN ?? -- operator lets you test a field against a list of values. ALL ?? -- operator lets you use a relational operator against a subselect & determine whether the condition is true for ALL values in the list. ANY ?? -- operator lets you use a relational operator against a subselect to determine whether the condition is true for SOME values in the list. Sorting by multiple columns the least important column is called?

Functions AVG SUM COUNT MAX MIN Use the __________ operator to select a count of unique values. DISTINCT A query within a query is called a ______________________. Nested Query/SubQuery What is evaluated first in a subquery? Inner Query

GROUPING -- examples rows for all customers who have the same sales rep rows for all customers who have the same credit limit rows for all customers who have the same balance When rows are grouped there is one row of output for each group The condition to set a Column name to unknown is ___________. NULL Joining tables you must? From clause -- Where clause

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