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Oracle PL/SQL More Aggregation – Rank

Oracle PL/SQL Aggregation  – Rank

One of the more interesting aggregation functions is RANK.  After doing a standard SELECT and GROUP BY; you can then have SQL rank the results using an aggregated value from another column.

Let’s dive in and look at how RANK works and what can it do for us.

Oracle 12c Limit Rows Returned

Limit Rows Returned

Previous to Oracle 12c limit the number of rows returned usually meant encapsulating the query as a subquery.  It wasn’t particularly nice looking and was out of alignment with other relational database query languages.

MySQL uses the LIMIT operator and Microsoft T-SQL uses the TOP operator. In Oracle 12c, Oracle introduced the FETCH FIRST operator.  Let’s see how it works.

Oracle PL/SQL Subtotal Operators

Oracle PL/SQL Subtotal Operators

There are times when we need not just the total value for the column, but subtotal values depending on different column values.  Oracle supports subtotal operators through the three key operators they are CUBE, ROLLUP, and GROUPING SETS. Below are examples of each one and how best to use them.

Aggregation in Oracle PL/SQL

Aggregation in Oracle PL/SQL

Oracle 12 uses normal SQL statements when doing aggregation.  The standard rules for aggregating in SQL apply.  You need to group by all non aggregated columns and having clause will be evaluated after the group by operator.

Some examples of aggregation in Oracle PL/SQL are below.

Dropping Tables in Oracle PL/SQL

Dropping Tables

Below are some examples of how to create tables in Oracle 12. PL/SQL, for the most part PL/SQL follows standard SQL conventions.

Creating Tables in Oracle 12 PL/SQL

Creating Tables

Below are some examples of how to create tables in Oracle 12. PL/SQL. For the most part PL/SQL follows standard SQL conventions.  I will show how to create some tables and some of the more popular options when creating tables.

SQLite Interface Class for R

SQLite Interface Class for R

I wrote an interface class to help with working with the SQLite database.

Methods include, selectQuery, updateQuery, readTable, writeTable

 

see code below

Datatype Cast in T-SQL

“Making a square peg fit into a round hole”

There are many times when dealing with data that you need to transfigure one data set to allow for comparison purposes.

SQL has built in functions that easily allow us to transfigure data. There are some considerations when using the functions, most importantly understanding what will happen to the data set during the process.

Today I will talk about the CAST function.

SQL Update Many Rows

When working with a large table the UPDATE statement can easily bring even the most robust server to a screeching halt. In this posting I will show an alternative so even the largest tables can be updated without negatively impacting server performance.

Updating a million rows

Microsoft Access and ANSI

“What you don’t know can’t hurt you can drive you bonkers.” – R. Hedgins

Today’s posting will deal with an option setting that can minimize interoperability issues between Microsoft’s nuanced interpretations of standards.

Microsoft Access and Microsoft SQL

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