SQL Operators and Operands
Database Operators and Operands
The fields we have been using allow the user to enter, view, or change data of a database. Because there is so many types of values a user can be ask to deal with, the values in the fields are categorized by types. Learn: Overview of Operators and Operands, Constants, Operators, Logical Operators.
Logical Operators in Access SQL
Originally, logical operators were a concept from algebra used to exclude and include number sets. They are, very simply, NOT, AND, and OR. Sometimes this set is expanded to combinations of the operators, but at core it's only these three. The logical operators are often referred to as the Boolean operators.
Table of operators
An operator is a sign or symbol that specifies the type of calculation to perform within an expression. There are mathematical, comparison, logical, and reference operators. Access supports a variety of operators, including arithmetic operators such as +, -, multiply (*), and divide (/), in addition to comparison operators for comparing values, text operators for concatenating text, and logical operators for determining true or false values. This article provides details about using these operators.
Exploring Data Analysis
To further enhance your filtering capabilities, you can use Boolean algebra combined with the operators we have used so far. Besides the logical operators we know already, Boolean algebra adds extra operators used to concatenate expression.
SQL - Multiple Conditions; using the AND and OR conditions
SQL allows us to combine two or more simple conditions by using the AND and OR or NOT operators. Any number of simple conditions can be present in a single SQL statement, to allow us to create complex WHERE clauses that allow us to control which rows are included in our query results.
Operators and Operands
Microsoft Access and Microsoft Visual Basic are not case-sensitive. Therefore, any word we are going to use that involves a field, its name, and new words we will introduce in this section, whether written in uppercase, lowercase or a mix, as long as it is the same word, represents the same thing. Based on this, the words TRUE, True and true, as related to Microsoft Access, represent the same word. In the same way, if the words NULL, Null, and null are used in an expression, they represent the same thing.
Tables and Relationships
Situation: I'm creating a database to keep track of earth moving activities. There are multiple operators (people operating the earth moving equipment). There are also multiple pieces of equipment.
In any given shift, multiple operators may use one piece of equipment. Similarly, one operator may use multiple pieces of equipment.
I'm thinking that I should create a table for all the operators, and then a table for all the equipment and establish a 'many to many' relationship between the primary key of the equipment(the equipments ID number) and the primary key of the operators table (the operators employee number).
Is this a valid structure, and is it one that can be implemented in Access?
Introduction to DAO, ADO, ADOX, and SQL
Microsoft Access ships with a language named Visual Basic For Applications, or VBA. This allows you to complement MS Access with code that can perform complex operations. This language is used throughout the Microsoft Visual Office family of applications, including Microsoft Excel, Work, PowerPoint, Visio, etc. This language is also used by applications published by companies other than Microsoft. An example is Autodesk that publishes AutoCAD. To customize the VBA language for our database environment, Microsoft Access includes a library called Microsoft Access Object Library.
Topics Microsoft Access Object Library and VBA, Microsoft Data Access Objects, Database Creation With DAO, The Structured Query Language, Introduction to SQL Operators, Unary Operators, Binary Operators, Microsoft ActiveX Data Objects, ADOX Fundamentals, The Data Source of an Application and The Connection to a Database.
List box with operators
I need to create a list box with operators and I'm having difficulty figuring out how to tell access that greater than = > and less than = < and or = or and so on
Query Criteria In Access 2010 Through Logical Operators
As the name implies, Query pulls out specific data from table fields included in database, thus, setting specific criterion in query helps you to filter down the table field data according to your needs. Through simple logical operators in Query Criteria you can set a criteria by using simple AND/OR operators, which lets you to confine the results of a query based upon the query criteria to check which table field data is to be included.
Nest a query inside another query or in an expression by using a subquery
Sometimes you may want to use the results of a query as a field in another query, or as a criterion for a query field. For example, suppose that you want to see the interval between orders for each of your products. To create a query that shows this interval, you need to compare each order date to other order dates for that product. Comparing these order dates also requires a query. You can nest this query inside of your main query by using a subquery (subquery: An SQL SELECT statement that is inside another select or action query.).
You can write a subquery in an expression (expression: Any combination of mathematical or logical operators, constants, functions, and names of fields, controls, and properties that evaluates to a single value. Expressions can perform calculations, manipulate characters, or test data.) or in a Structured Query Language (SQL) statement in SQL view (SQL view: A window that displays the SQL statement for the current query or that is used to create an SQL-specific query (union, pass-through, or data definition). When you create a query in Design view, Access constructs the SQL equivalent in SQL view.).
SQL Server vs Access JOIN Syntax
I was trying to use the Access query builder to speed up the creation of a SELECT statement.. so I do not make a typo in one of the column names.
I have been aware that Access prefers complex / messy JOIN syntax, involving many () operators. So, wishing to trick it into using neat and tidy JOIN syntax which SQL Server accepts, I changed its JOIN text to the format SQL Server accepts.. taking care not to mess up the Access Linked Table names which are different than the actual SQL Server names, slightly.
That done, Access will not accept the simplified JOIN syntax!
SQL that works in SQL Server Management Console:
Access (non pass through) version which "should" work:
Error message is:
"Syntax error (missing operator) in query expression"
And it gives a large portion of the JOIN area of the query. I used a text editor to swap out the underscore deliminator character for the SQL Server ].[ syntax to switch from the Access version to SQL Server. NO OTHER EDITS! So I know the Access version "should" work....
SQL Where and Between
I'm trying to make an SQL statment which contain both the where and between
DoCmd.RunSQL "UPDATE MuhurDB SET location = " & Me.Location & " WHERE Grup =" & Chr(39) & grup & Chr(39) & " AND WHERE muhur BETWEEN " & fromTxt & " AND " & tillTxt
I get the error message about missing operators Error: 3075
Microsoft Access Query Operators
Queries are a very important feature of Microsoft Access that can tell you information about the data stored in the Access tables. Queries make it easier to search the data from different fields. Therefore, using queries to achieve the results you are looking for is quite a useful tool. However, when you have large amounts of information, you will need more advanced techniques such as Boolean Operators to make sense of the queries you have inputted.
Multiple validations in same field
I need to enter into a field either Null OR "N" OR "Pn" The Pn is a unique number between P001 and P999.
Obviously the "no duplicates" rule for Pn will interfere with the "N" entries. Is there a way around this?
Alternately, the operators who enter Null or "N" use one form, and the operators who enter Null or Pn use a different form. Is it possible to create different validation rules that are tied to the respective forms?
Multiple validations in same field
I need to enter into a field either Null OR "N" OR "Pnnn" The Pnnn is a unique number between P001 and P999.
Obviously the "no duplicates" rule for Pnnn will interfere with the "N" entries. Is there a way around this?
Alternately, the operators who enter Null or "N" use one form, and the operators who enter Null or Pnnn use a different form. Is it possible to create different validation rules that are tied to the respective forms
viewing data in report before saved to table.
Need information in form to write to report before accepted and saved to separate table, so operators can read it.
background:manifest information entered into form in receiving office, analysis ran in lab and then entered into form. When analysis is approved, Operators unload material then truck checks out in receiving office.
Need to see analysis before it is written from load_temp table to Load table.
Convert Microsoft Access (JET SQL) to SQL Server (T-SQL) Cheatsheet
Lots of questions come up in the SQL Team forums about conversions between Access and T-SQL and some of the differences between the two SQL dialects. Here's a few handy things to help you out with converting your projects. Check in now and then as this short list will eventually grow as more things come up.
"Complicated" Query - aggregate functions for several columns
I have a table called Transaction that is used for web chat data. It has the following fields:
Date Time Duration Wait Operator
I need to count the number of chat sessions per day (that is, count the number of rows for each distinct date), and count the number of different Operators per day. I also need to take the average duration of the day's chat sessions.
In several queries, I can come up with the total chat sessions by day, and the number of operators per day, but am not able to include any daily averages of duration or wait times
A quick commentary on Access
I read recently that there is a command in Windows (Shadow Volume) that allows you to back up an open file. If that is the case could it be used With Access to back up the data files for a multi-user application on a regular basis. If that is the case then would this negate the use of going to SQL Server when smaller data files (2G limit for Access) are concerned. If a backup every 15 minutes was scheduled could that be a viable work around for small business operators. I know some data may get lost if a crash does occur but it may be an acceptable trade off for some business types. Just throwing it out there for your comments