kode php

Cara menggunakan php sqlite parameterized query

Example

Return the number of products in the "Products" table:

SELECT COUNT(ProductID) AS NumberOfProducts FROM Products;

Try it Yourself »

Definition and Usage

The COUNT() function returns the number of records returned by a select query.

Note: NULL values are not counted.

Syntax

Parameter Values

ParameterDescriptionexpressionRequired. A field or a string value

Technical Details

The SELECT statement is used to make a simple query from a database or a complicated query against some criteria. A SELECT statement does not make any changes to the database.

A query or SELECT statement is a command which gives instructions to a database to produce certain information(s) from the table in its memory. The SELECT command starts with the keyword SELECT followed by a space and a list of comma separated columns. A * character can be used to select all the columns of a table. The table name comes after the FROM keyword and a white-space.

Syntax:

SELECT [ALL | DISTINCT] result [FROM table-list] [WHERE expr] [GROUP BY expr-list] [HAVING expr] [compound-op select]* [ORDER BY sort-expr-list] [LIMIT integer [(OFFSET|,) integer]]

Parameters:

ClauseOperation performInput ValueWHEREUsed to restrictExpression or conditionDISTINCTUsed to restrictList of columnsFROMJoinsList of tablesGROUP BYUsed to restrictList of columnsORDER BY List of columnsHAVINGUsed to restrictExpression or conditionLIMITUsed to restrictInteger valueOFFSETUsed to restrictInteger value

Here is the sample table employees.

Examples:

Retrieving all data:

If you want to retrieve all the rows from the locations table the following SQL can be used.

SELECT * FROM locations;

Relational Algebra Expression:

Relational Algebra Tree:

Here is the result.

sqlite> SELECT * FROM locations; location_id street_address postal_code city state_province country_id ----------- -------------- ----------- ---------- -------------- ---------- 1000 1297 Via Cola 989 Roma IT 1100 93091 Calle de 10934 Venice IT 1200 2017 Shinjuku- 1689 Tokyo Tokyo Prefectu JP 1300 9450 Kamiya-ch 6823 Hiroshima JP 1400 2014 Jabberwoc 26192 Southlake Texas US 1500 2011 Interiors 99236 South San California US 1600 2007 Zagora St 50090 South Brun New Jersey US 1700 2004 Charade R 98199 Seattle Washington US 1800 147 Spadina Av M5V 2L7 Toronto Ontario CA 1900 6092 Boxwood S YSW 9T2 Whitehorse Yukon CA 2000 40-5-12 Laogia 190518 Beijing CN 2100 1298 Vileparle 490231 Bombay Maharashtra IN 2200 12-98 Victoria 2901 Sydney New South Wale AU 2300 198 Clementi N 540198 Singapore SG 2400 8204 Arthur St London UK 2500 Magdalen Centr OX9 9ZB Oxford Oxford UK 2600 9702 Chester R 9629850293 Stretford Manchester UK 2700 Schwanthalerst 80925 Munich Bavaria DE 2800 Rua Frei Canec 01307-002 Sao Paulo Sao Paulo BR 2900 20 Rue des Cor 1730 Geneva Geneve CH 3000 Murtenstrasse 3095 Bern BE CH 3100 Pieter Breughe 3029SK Utrecht Utrecht NL 3200 Mariano Escobe 11932 Mexico Cit Distrito Feder MX

Here in the above example the * have been used to indicate ALL the records from the locations table.

if FROM clause not used:

An expression can only be executed:

sqlite> SELECT 6+15; 6+15 ---------- 21 or sqlite> SELECT 5*15; 5*15 ---------- 75 or sqlite> SELECT 5+2-3*4/6; 5+2-3*4/6 ---------- 5

Select specific columns:

The SELECT statement can be used to retrieve specific columns. The column names follow the SELECT word.

If you want to retrieve the columns street_address and city from the location table the following SQL can be used.

SELECT street_address, city FROM locations;

Relational Algebra Expression:

Relational Algebra Tree:

Here is the result.

sqlite> SELECT street_address, city FROM locations; street_address city -------------------------------------------------- ---------- 1297 Via Cola di Rie Roma 93091 Calle della Testa Venice 2017 Shinjuku-ku Tokyo 9450 Kamiya-cho Hiroshima 2014 Jabberwocky Rd Southlake 2011 Interiors Blvd South San 2007 Zagora St South Brun 2004 Charade Rd Seattle 147 Spadina Ave Toronto 6092 Boxwood St Whitehorse 40-5-12 Laogianggen Beijing 1298 Vileparle (E) Bombay 12-98 Victoria Street Sydney 198 Clementi North Singapore 8204 Arthur St London Magdalen Centre, The Oxford Science Park Oxford 9702 Chester Road Stretford Schwanthalerstr. 7031 Munich Rua Frei Caneca 1360 Sao Paulo 20 Rue des Corps-Saints Geneva Murtenstrasse 921 Bern Pieter Breughelstraat 837 Utrecht Mariano Escobedo 9991 Mexico Cit

Select columns using alias:

In the FROM list with a select statement, one or more table names can be included separated by a comma. The tables using followed by the FROM clause have an optional alias name that can be used to mention individual column names in the result.Where the table name in full can be used to qualify columns of a table, the aliases are not used.

sqlite> SELECT regions.region_name FROM regions; region_name ------------------------- REGION_NAME Europe Americas Asia Middle East and Africa or sqlite> SELECT z.region_name FROM regions z; region_name ------------------------- REGION_NAME Europe Americas Asia Middle East and Africa

Here in the above, the two SELECT statements are identical, the latter uses a table alias z for regions.

Renaming column names :

Sometimes we use the column name as short form against a keyword for that column. So the return value for that column will appear in short from, and sometimes we required to display it in full name. It can be done by using the AS clause followed the column name or any expression with the select statement.

If you want to retrieve the region_name column from the regions table with the customize column head "Name of the Region" the following SQL can be used. If the customize heading contain more than one words then it will be within a quote unquote unless it can be used independently.

Here is the example.

SELECT region_name AS "Name of the Region" FROM regions;

Here is the result.

Name of the Region ------------------------- REGION_NAME Europe Americas Asia Middle East and Africa

Here in the following example, the customize heading contain more than one words and it used without quote unquote, and this statement occurs an error.

sqlite> SELECT region_name AS Name of the Region FROM regions; Error: near "of": syntax error

Limit Output:

When we want to retrieve a limited amount of data from a large database we can use the LIMIT clause to limit the data amount returned by the statement.

If we want to retrieve the first ten records from the locations table, the following SQL can be used.

SELECT * FROM locations; 0

Here is the result.

SELECT * FROM locations; 1

If we want to retrieve five records skipping the first four from the locations table, the following SQL can be used.

SELECT * FROM locations; 2

Here is the results.

SELECT * FROM locations; 3

Select using OFFSET clause:

The OFFSET clause after LIMIT specifies how many rows to skip at the beginning of the result set.

Here is the example.

SELECT * FROM locations; 4

Here is the result is same as the previous result.

SELECT * FROM locations; 5

WHERE clause

WHERE is a powerful filter A WHERE clause can let you take exactly the piece of the data you want. It sets the conditions for the SELECT, and the query will return only those rows that match the conditions. It provides you with a great degree of control over the conditions to impose restrictions on the dataset returned by a SELECT with which to include (or exclude) rows in (or from) the result. It is used both to limit the number of rows returned and to indicate a relationship used to join two tables together.

If you only wanted to see cities from Canada, the following SQL can be used.

SELECT * FROM locations; 6

Relational Algebra Expression:

Relational Algebra Tree:

Here is the result for the above statement.

SELECT * FROM locations; 7

Here some operators can be used with WHERE clause. Here are the operators below-

operatordescription=Equal<>Not equal*>Greater than<Less than>=Greater than or equal<=Less than or equal

Here is a sample table agents.

SELECT * FROM locations; 8

If you only wanted to see agent_code, agent_name, and commission from the agents who gets the commission less than .15% , the following SQL can be used.

SELECT * FROM locations; 9

Here is the result for the above statement.

If you only wanted to see agent_code, agent_name, and commission from the agents who gets the commission more than .12% , the following SQL can be used.

Here is the result for the above statement.

If you only want to see cities from Canada, the following SQL can be used.

Relational Algebra Expression:

Relational Algebra Tree:

Here is the result for the above statement.

SELECT * FROM locations; 7

WHERE with AND and OR

You can using AND and OR with WHERE clause for filter the rows from the tables.

Here is the sample table employees:

If you want to see the employee_id, first_name, last_name, job_id, manager_id and departments who belongs to the department_id 80, the following SQL can be used.

Relational Algebra Expression:

Relational Algebra Tree:

Here is the result.

Sample Output:

Here in the another example, if you want to see the employee_id, first_name, last_name, job_id, manager_id and departments who belongs to the department_id 80, and must be under the manager whose ID is 100, the following SQL can be used.

Relational Algebra Expression:

Relational Algebra Tree:

Here is the result.

Now, lets find those employees, whose job ID may be CLERK or may be in the department which ID is 80 and must be under the manager who is the owner of the ID 147.

Here is the statement.

Relational Algebra Expression:

Relational Algebra Tree:

Here is the result of the above statement.

sqlite> SELECT 6+15; 6+15 ---------- 21 or sqlite> SELECT 5*15; 5*15 ---------- 75 or sqlite> SELECT 5+2-3*4/6; 5+2-3*4/6 ---------- 5 0

The anove result shows that, the 'SA_REP' job_id also appear along with 'SH_CLERK', because the implimentation of OR clause and manager_id 147 appear for only those departments that have the ID 80.

The AND operator has a higher precedence than the OR operator, which means it gets evaluated first. So, in effect, the query really looks like the below:

sqlite> SELECT 6+15; 6+15 ---------- 21 or sqlite> SELECT 5*15; 5*15 ---------- 75 or sqlite> SELECT 5+2-3*4/6; 5+2-3*4/6 ---------- 5 1

Relational Algebra Expression:

Relational Algebra Tree:

Which selects all employees for 'SH_CLERK' and only those employees for department no 80 who have under the manager whose id is 147. The parentheses can be used to clarify the query and actually get the high rollers we wanted.

DISTINCT

The DISTINCT keyword is used to select only unique items from the result set or it can be said that, it eliminates the duplicates rows from the result of the query.

If you want to get the unique department_id and manager_id combination , the following SQL can be used.

sqlite> SELECT 6+15; 6+15 ---------- 21 or sqlite> SELECT 5*15; 5*15 ---------- 75 or sqlite> SELECT 5+2-3*4/6; 5+2-3*4/6 ---------- 5 2

Relational Algebra Expression:

Relational Algebra Tree:

Here is the result.

sqlite> SELECT 6+15; 6+15 ---------- 21 or sqlite> SELECT 5*15; 5*15 ---------- 75 or sqlite> SELECT 5+2-3*4/6; 5+2-3*4/6 ---------- 5 3

The above result shows only the unique combination of department_id and manager_id have appeared. Now, if we add the job_id column with above query, look what will happen.

sqlite> SELECT 6+15; 6+15 ---------- 21 or sqlite> SELECT 5*15; 5*15 ---------- 75 or sqlite> SELECT 5+2-3*4/6; 5+2-3*4/6 ---------- 5 4

Relational Algebra Expression:

Relational Algebra Tree:

Here is the output.

sqlite> SELECT 6+15; 6+15 ---------- 21 or sqlite> SELECT 5*15; 5*15 ---------- 75 or sqlite> SELECT 5+2-3*4/6; 5+2-3*4/6 ---------- 5 5

Here in the above result, the unique combination made by three columns and a naturally number of rows become changed, and here more rows appear than before.

ORDER BY

The ORDER BY clause is used to sort the returned data set. The ORDER BY clause is followed by the column on which we do the sorting. The default direction for ORDER BY is ascending; results are ordered from smallest amount to greatest. To specify the direction of the ORDER BY, use the DESC or ASC keyword:

If you want to sort the result according to salary for those employees which department no. is below 50, the following SQL can be used.

sqlite> SELECT 6+15; 6+15 ---------- 21 or sqlite> SELECT 5*15; 5*15 ---------- 75 or sqlite> SELECT 5+2-3*4/6; 5+2-3*4/6 ---------- 5 6

Relational Algebra Expression:

Relational Algebra Tree:

Here is the result.

sqlite> SELECT 6+15; 6+15 ---------- 21 or sqlite> SELECT 5*15; 5*15 ---------- 75 or sqlite> SELECT 5+2-3*4/6; 5+2-3*4/6 ---------- 5 7

If you want to sort the result according to salary in descending order for those employees which department no. is below 50 , the following SQL can be used.

sqlite> SELECT 6+15; 6+15 ---------- 21 or sqlite> SELECT 5*15; 5*15 ---------- 75 or sqlite> SELECT 5+2-3*4/6; 5+2-3*4/6 ---------- 5 8

Relational Algebra Expression:

Relational Algebra Tree:

Here is the result.

sqlite> SELECT 6+15; 6+15 ---------- 21 or sqlite> SELECT 5*15; 5*15 ---------- 75 or sqlite> SELECT 5+2-3*4/6; 5+2-3*4/6 ---------- 5 9

The result of the query can be ordered by more than one column. Rows with the same value for the first column of the ORDER BY are further ordered by the additional column(s):

Here is the example.

If you want to order the result firstly by department_id column in ascending order and after that, which departments are same they will be ordered themselves descendingly according to the salary, the following SQL can be used.

SELECT street_address, city FROM locations; 0

Relational Algebra Expression:

Relational Algebra Tree:

Here is the result.

SELECT street_address, city FROM locations; 1

It seems to the above result that, depertment_id 20 and 30 have more than one rows, and they have been arranged descendingly according to the salary, that is the greatest salary will come first.

ORDER BY with DISTINCT

If you want to get the unique department_id, manager_id and job_id combination by an order according to department ascendingly, the following SQL can be used.

SELECT street_address, city FROM locations; 2

Relational Algebra Expression:

Relational Algebra Tree:

Here is the output.

SELECT street_address, city FROM locations; 3

GROUP BY

The GROUP BY clause is used to combine database records with identical values into a single record. It is often used with the aggregation functions.

The GROUP BY clause is used to aggregate data into a single row where the value of one or more specified columns is repeated. It is used to combine database records with identical values into a single record. It is often used with the aggregation functions. The GROUP BY clause takes a list of expressions, usually column names from the result, and aggregates data for each expression. The job of the GROUP BY clause is to compute aggregates over an entire result, and can also split that result into groups of rows with specified values, and compute aggregates on each group, in a single step.

The GROUP BY clause sits in between the WHERE clause and the SELECT clause. It gets the output from WHERE and splits it into groups of rows that share a common value (or values) for a specific column (or columns). These groups are then passed to the SELECT clause.

The grouping process performed by two steps. First, the GROUP BY expression arranged the table rows into different groups. Once the groups are defined, the SELECT header defines how those groups are flattened down into a single row. The resulting table will have one row for each group.

If you want to find the total salary required for a month, which is on or above one lacs, for the designation that holding the ID is below 80, by an order of largest to smallest salary the following SQL can be used.

Cara menggunakan php sqlite parameterized query

Example

Definition and Usage

Syntax

Parameter Values

Technical Details

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