How do you write a query to display all records?

How do you write a query to display all records?
Select command is used to collect date from the table. We will discuss more on this by adding more commands to this select command. Understand Structured Query Language ( SQL ) and read the basics of database table here.

SELECT query with LIMIT and order by with WHERE condition checking using BETWEEN range

20 SELECT queries with WHERE BETWEEN AND OR IN LIKE commands to get data from SQLite database

Full student table with SQL Dump


Now your table with some data is ready. We will apply select command to our table ( name student ) and fetch all the records SELECT * FROM `student`
idnameclassmark
1John DeoFour75
2Max RuinThree85
3ArnoldThree55
4Krish StarFour60
5John MikeFour60
6Alex JohnFour55
7My John RobFifth78
8AsruidFive85
9Tes QrySix78
10Big JohnFour55
That's all to get all the records from the table student. We have not placed any restriction here and asked for all the fields with all the records. Now if we want to restrict our results and get only name field from the table.SELECT name FROM `student` This will return only name field from the table. We can ask for more fields and all field names we have to separate by comma. We can include as many field names we want from a table. SELECT name, class FROM `student`
nameclass
John DeoFour
Max RuinThree
ArnoldThree
Krish StarFour
John MikeFour
Alex JohnFour
My John RobFifth
AsruidFive
Tes QrySix
Big JohnFour
Now we will go for bit more and restrict the number of records we are getting. We are interested say in only 3 records. Our command should return 3 records only. We will use SQL limit command. This will take two parameters. One is the starting point and other is number of records required. Say we are interested in 3 records starting from beginning. Our command will be
SELECT * FROM `student` LIMIT 0,3

Related Tutorial Copy data to new table SQL Left Join SQL UNION

This command with LIMIT command will return us 3 records starting from 0 ( or first ) record. This is very important when we use this command with ORDER BY command. Now let us try to list all the students who have come in first 3 ranks. We are required to list here 3 records who have mark more than the others. The top 3 students we want to display in order of first, second and third. The order we can display are in by default in ascending order but we require the listing should return in descending order so we will get the highest ranked student at the top. Before that let us start with a simple example of ORDER BY command.
SELECT * FROM `student` ORDER BY mark This will display the records of students in the order of lowest mark to highest mark.
idnameclassmark
19TinnyNine18
17TumyuSix54
10Big JohnFour55
22ReggidSeven55
29Tess PlayedSeven55
6Alex JohnFour55
3ArnoldThree55
5John MikeFour60
4Krish StarFour60
20JacklyNine65
We will change it to display in reverse order so it will display highest mark at the top and lowest mark at the bottom.
SELECT * FROM `student` ORDER BY `mark` DESC With the addition of command DESC we can change the order of display to keep the highest mark at the top of the list and lowest mark at the bottom of the list. Now let us add the LIMIT command to display only the top 3 records. We already have the list in the order of highest mark to lowest mark so by just limiting the number of records to 3 will give our required top three student records.
SELECT * FROM `student` ORDER BY `mark` DESC LIMIT 0,3
idnameclassmark
33Kenn ReinSix96
12ReckySix94
32Binn RottSeven90
This is the SQL query which will display top three students  based on the mark they scored. In the next section we will use sql WHERE clause to restrict or filter the records.

Combining two columns and displaying them as one

We can use CONCAT function to combine two columns and displaying them as one column. For example we can combine first name and last name and display them as Name.

Sample code in PHP

How do you write a query to display all records?
We have to first connect to database using PHP PDO. Then we can display the records by looping. Here is the sample code to display 4 records. However any other query can be used and matching records can be displayed. <?Php require "config.php";// Database connection $count="SELECT * FROM student LIMIT 0,4"; echo "<table>"; echo "<tr><th>id</th><th>name</th><th>class</th> <th>mark</th></tr>"; foreach ($dbo->query($count) as $row) { echo "<tr ><td>$row[id]</td><td>$row[name]</td> <td>$row[class]</td><td>$row[mark]</td></tr>"; } echo "</table>"; ?> Full student table with SQL Dump
What is SQL Query with WHERE Condition Collecting data by linking more than one table
How do you write a query to display all records?


This article is written by plus2net.com team. https://www.plus2net.com


How do you write a query to display all records?

plus2net.com

▼ More on getting records from table with different combinations of commands

raju

11-04-2013

How to get ( select ) data from more than one table ?

ranj

01-01-2014

how to get 200 characters/letters from a long description and to be followed by "..."

midhu

09-03-2015

how to display data in database as table by some limit(first 10,first 20,all) using php

smo

09-03-2015

You can display by using above code or to display first 10 you can use LIMIT query. By adding Order by to the query you can display in the order of highest to lowest or alphabetically or in any other combination.

Daniel

08-07-2015

smo:::How to get ( select ) data from more than one table ?

Vivek Kumar Tyagi

12-09-2015

in last example .. what is $dbo??

smo1234

12-09-2015

It is declared inside config.php file where all database connection details are kept. The link is there also.

When you want to select specific data from one or more sources, you can use a select query. A select query helps you retrieve only the data that you want, and also helps you combine data from several data sources. You can use tables and other select queries as data sources for a select query. This topic provides an overview of select queries, and gives steps for creating a select query, by using the Query Wizard or in Design view.

If you want to use the Northwind sample database to learn more about how queries work, see the article Introduction to queries.

When you want to use data, you rarely want to use all of the data from one table. For example, when you want to use data from a Contacts table, you usually want to look at one specific record, or maybe just the telephone number. Sometimes you want to combine data from more than one table, such as combining Customer information with Order information. To select the data that you want to use, you use a select query.

A select query is a database object that shows information in Datasheet view. A query does not store data, it displays data that is stored in tables. A query can show data from one or more tables, from other queries, or from a combination of the two.

A query lets you:

  • View data only from the fields you are interested in viewing. When you open a table, you see all the fields. A query is a handy way to save a selection of fields.

    Note: A query only points to data, it does not store data. When you save a query, you are not saving a copy of the data.

  • Combine data from several data sources. A table usually only displays data that it stores. A query lets you pick and choose fields from various sources, and specify how the information should be combined.

  • Use expressions as fields. For example, you could use the Date function as a field, or you could use the Format function with a field to control the way the data from the field is formatted in the query results.

  • View records that meet criteria that you specify. When you open a table, you see all the records. A query is a handy way to save a selection of records.

You can create a select query by using the Query Wizard or by working in Design view. Some design elements are not available when you use the wizard, but you can add these elements later by using Design view. Although the two methods are somewhat different from each other, the basic steps are essentially the same:

  1. Choose the tables or queries that you want to use as sources of data.

  2. Specify the fields that you want to include from the data sources.

  3. Optionally, specify criteria to limit the records that the query returns.

After you have created a select query, you run it to see the results. To run a select query, you open it in Datasheet view. If you save the query, you can reuse it whenever you need, for example, as a data source for a form, report, or another query.

You can use the Query Wizard to automatically create a select query. When you use the wizard, you have less control over the details of the query design, but the query is usually created faster than if you did not use the wizard. Moreover, the wizard can catch some simple design mistakes and prompt you to perform a different action.

If you use fields from data sources that are not related to each other, the Query Wizard asks you if you want to create relationships. The wizard opens the Relationships window for you, but you must restart the wizard if you edit any relationships. Therefore, before you run the wizard, consider creating any relationships that your query needs.

For more information about creating table relationships, see the article Guide to table relationships.

  1. On the Create tab, in the Queries group, click Query Wizard

    How do you write a query to display all records?
  2. In the New Query dialog box, click Simple Query Wizard, and then click OK.

  3. Next, you add fields. You can add up to 255 fields from as many as 32 tables or queries.

    For each field, perform these two steps:

    1. Under Tables/Queries, click the table or query that contains the field.

    2. Under Available Fields, double-click the field to add it to the Selected Fields list. If you want to add all fields to your query, click the button with the double right arrows (>>).

    3. When you have added all the fields that you want, click Next.

      How do you write a query to display all records?
  4. If you did not add any number fields (fields that contain numeric data), skip ahead to step 9. If you added any number fields, the wizard asks whether you want the query to return details or summary data.

    Do one of the following:

    1. If you want to see individual records, click Detail, and then click Next. Skip ahead to step 9.

    2. If you want to see summarized numeric data, such as averages, click Summary, and then click Summary Options.

      How do you write a query to display all records?
  5. In the Summary Options dialog box, specify which fields you want to summarize, and how you want to summarize the data. Only number fields are listed.

    For each number field, choose one of the following functions:

    1. Sum    The query returns the sum of all the values of the field.

    2. Avg    The query returns the average of the values of the field.

    3. Min    The query returns the smallest value of the field.

    4. Max    The query returns the largest value of the field.

    How do you write a query to display all records?
  6. If you want the query results to include a count of the records in a data source, select the appropriate Count records in data source name check box.

  7. Click OK to close the Summary Options dialog box.

  8. If you did not add a date/time field to the query, skip ahead to step 9. If you added a date-time field to the query, the Query Wizard asks you how you would like to group the date values. For example, suppose you added a number field ("Price") and a date/time field ("Transaction_Time") to your query, and then specified in the Summary Options dialog box that you want to see the average value of the number field "Price". Because you included a date/time field, you could calculate summary values for each unique date/time value, for each day, for each month, for each quarter, or for each year.

    How do you write a query to display all records?

    Select the time period that you want to use to group the date/time values, and then click Next.

    Note: In Design view, you can use an expression to group by any time period you want, but the wizard only offers these choices.

  9. On the last page of the wizard, give the query a title, specify whether you want to open or modify the query, and then click Finish.

    If you choose to open the query, the query displays the selected data in Datasheet view. If you choose to modify the query, the query opens in Design view.

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You can use Design view to manually create a select query. When you use Design view, you have more control over the details of the query design, but it is easier to make design mistakes, and it can take longer than using the wizard.

When you use Design view, to add data sources, you add the data sources and fields in separate steps. However, you can always add more data sources later if you want.

  1. On the Create tab, in the Other group, click Query Design

    How do you write a query to display all records?
  2. Double-click each data source that you want to use or select each data source and then click Add.

    How do you write a query to display all records?

When you add the data sources, if the sources already have relationships defined between them, those relationships are automatically added to the query as joins. Joins specify how data from related sources should be combined. Access also automatically creates a join between two tables if they have fields have compatible data types and one field is a primary key.

You might want to adjust the joins that Access creates. Access determines what type of join to create based on the relationship the join represents. If Access creates a join but there is no defined relationship, Access creates an inner join.

If Access automatically creates the correct joins when you add the data sources, you can skip ahead to Step 3: Add output fields.

In some cases, you want to join two copies of the same table or query, called a self-join, that combines records from the same table when there are matching values in the joined fields. For example, say you have an Employees table in which the ReportsTo field for each employee's record displays his or her manager's ID instead of name. You could use a self-join to display the manager's name in each employee's record instead.

When you add a data source a second time, Access appends _1 to the name of the second instance. For example, if you added the Employees table twice, the second instance would be named Employees_1.

If the data sources that you add to a query already have relationships, Access automatically creates an inner join for each relationship. If referential integrity is enforced, Access also displays a "1" above the join line to show which table is on the "one" side of a one-to-many relationship and an infinity symbol () to show which table is on the "many" side.

If you add queries to your query, and have not created relationships between those queries, Access does not automatically create joins between those queries, or between queries and tables that are not related. If Access does not create joins when you add data sources, you should usually add them yourself. Data sources that are not joined to any other data source can cause problems with the query results.

You might also want to change the type of a join from an inner join to an outer join, so that your query includes more records.

  • To add a join, drag a field from one data source to a corresponding field on another data source.

    Access displays a line between the two fields to show that a join has been created.

    How do you write a query to display all records?
  1. Double-click the join you want to change.

    The Join Properties dialog box appears.

    How do you write a query to display all records?
  2. In the Join Properties dialog box, review the three options.

  3. Click the option that you want to use, and then click OK.

After the joins are ready, you add output fields — fields that have data that you want in the query results.

You can easily add a field from any of the data sources that you added in step 1.

  • To add a field, drag the field from a data source in the upper pane of the query design window down to the Field row of the design grid, in the bottom pane of the query design window.

    When you add a field this way, Access automatically fills in the Table row of the design grid to reflect the data source of the field.

    Tip: If you want to quickly add all fields down to the Field row of the query design grid, double-click the table or query name from the upper pane to highlight all the fields in that source and then drag them all down to the design grid at the same time.

If you want to perform calculations or use a function to produce query output, you can use an expression as an output field. An expression can use data from any of the query data sources, as well as functions, such as Format or InStr, and can also contains constants and arithmetic operators.

  1. In an empty column of the query design grid, right-click the Field row, and then click Zoom on the shortcut menu.

  2. In the Zoom box, type or paste your expression. Preface your expression with the name you would like to use for the expression output, followed by a colon. For example, if you wanted the expression to be labeled "Last updated", you would start your expression with Last updated:.

    Note: You can do a wide variety of things by using expressions. A thorough explanation of expressions is beyond the scope of this article. For more information about creating an expression, see the article Build an expression.

This step is optional.

You use criteria to limit the records that your query returns, on the basis of whether field values meet the criteria that you specify.

  1. In the query design grid, in the Criteria row of the field that has values that you want to limit, type an expression that field values must satisfy to be included in your results. For example, if you wanted to limit a query so that only records where the value of the field City is Las Vegas, type Las Vegas in the Criteria row under that field.

    For many examples of query criteria for various data types, see the article Examples of query criteria.

  2. Specify any alternate criteria in the Or row, below the Criteria row.

    If you specify alternate criteria, a field value can meet any of the listed criteria and be included in the query result.

You can use criteria with multiple fields. When you do, all the criteria in a given Criteria or Or row must be true for the record to be included.

You can add a field to your query design and not include the field's data in the query output. You do this if you want to use the field's values to limit the query results, but don't want to see the field values.

  1. Add the field to the design grid.

  2. Clear the check box in the Show row for the field.

  3. Specify criteria as you would for an output field.

This step is optional.

You might want to summarize data, especially if your data is numeric. For example, you might want to see the average price, or total sales.

To summarize data in a query, you use the Total row. By default, the Total row is not displayed in Design view.

  1. With the query open in Design view, on the Design tab, in the Show/Hide group, click Totals.

    Access displays the Total row in the query design grid.

  2. For each field that you want to summarize, choose the function to use from the list in the Total row. The functions that are available depend on the data type of the field.

    To learn more about the Total row functionality in queries, see the article Sum or count values on a datasheet with a Total row.

To see the query results, on the Design tab, click Run. Access displays the results of your query in Datasheet view.

To make further changes to the query, click Home > View > Design View to switch back to Design view.

Change your fields, expressions, or criteria and rerun the query until it returns the data that you want.

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