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Fetch and Filter data in SQL

This guide shows you how to retrieve and filter data by using a variety of SQL clauses.

Prerequisites​

App Connected to PostgreSQL datasource.

info

When prepared statements are enabled and widget bindings are used, quotes are not required.

Using WHERE Clause​

The WHERE clause in SQL filters data based on specific conditions, enabling you to retrieve rows that match your criteria.

Example 1: If you want to filter Table data based on specific criteria, such as gender, you can use a Select widget with the required option.

Configure the query to fetch data using selectedOptionValue reference property, like:

-- With prepared statements enabled
SELECT * FROM users WHERE gender = {{Select1.selectedOptionValue}};

Learn more about Server-side Filter on Table.

Example 2: If you want to create a dynamic WHERE clause query that depends on user input, such as allowing users to specify a name using an Input widget, prepared statements can't be effectively used in these cases because the structure of the query is not static.

  1. Configure the query to fetch data using text reference property, like:
-- With prepared statements disabled
SELECT * FROM users WHERE {{ Input1.text ? "name = '" + Input1.text + "'" : "1=1" }}
  1. Turn Off the Prepared Statements.

Learn more about Prepared Statements.

caution
  • Using the IS keyword in MySQL is not supported in Appsmith. Use the = operator instead.
  • true / false values should be without quotes i.e. {{true}} instead of {{”true”}}.

Server-side pagination​

Server-side pagination allows you to manage and display large datasets within your application. It involves fetching and displaying only a portion of data from the server at a time, enhancing performance.

You can use either a Table or List widget to display the paginated data, and you can implement pagination with offset or cursor-based techniques by using the reference properties of these widgets.

Example:

  1. Create a query to fetch data from the database using pageSize, and pageOffset reference properties:
SELECT * FROM users LIMIT {{ Table1.pageSize }} OFFSET {{ Table1.pageOffset }};

  1. Connect the query data to the Table data property of the Table widget.

  2. Set the Table widget's onPageChange event to run the pagination query.

Learn more about Server-side Pagination on Table and Server-side Pagination on List.

Using conditional operators​

Conditional operators, like the AND operator, allow you to specify multiple conditions in your SQL queries. This can be handy when you need to narrow down your data retrieval based on several criteria.

Example: If you want to allow users to filter data for specific date ranges, such as retrieving data of users within a certain date range.

Configure the query to fetch data using selectedDate reference property, like:

-- With prepared statements enabled
SELECT * FROM users WHERE dob > {{DatePicker1.selectedDate}} AND dob < {{DatePicker2.selectedDate}} ORDER BY id;

Using LIKE or ILIKE operator​

If you want to perform search operations in your SQL queries, consider using LIKE or ILIKE operators, depending on your need for case sensitivity and partial matching. These operators enable pattern-based searches within your text data.

  • The % character, which is used as a wildcard in LIKE and ILIKE patterns, needs to be inside the mustache binding {{}}.
  • Do not enclose the mustache binding {{}} within quotes.

Example:If you want to perform a partial text search that matches the search term anywhere in the data column, you can use the following query with prepared statements enabled:

-- With prepared statements enabled
SELECT * FROM public.users where name ilike {{"%" + Table1.searchText + "%"}}

Using IN clause​

The IN clause in SQL allows you to filter results based on multiple values.

Example : If you're working with a list of product IDs as strings, you can use this query format:

-- With prepared statements disabled
SELECT * FROM products WHERE product_id IN {{productIDList}};
-- productIDList = ["productID1", "productID2", ...]

This query uses a single mustache binding {{productIDList}} to represent an array of product IDs, where productIDList is expected to be an array like ["productID1", "productID2", ...].

If you want to filter data based on countries selected in a Multi-select widget, turn off prepared statements for this query and use the following format:

-- With prepared statements disabled
SELECT * FROM public.users where country IN ({{MultiSelect2.selectedOptionValues.map(value => "'" + value + "'").join(', ')}});

Using ANY clause​

When working with IN statements, you may encounter situations where it's more convenient to use the ANY statement. The ANY keyword provides an alternative approach to achieving the same result.

  • When using this approach, provide all individual values in the list together, without separating them.
  • Do not enclose the mustache binding {{}} within quotes.

Example : If you want to filter employee data based on a specific combination of name and department, you can use the following query:

--Recommended format:
SELECT * FROM public."employees" where name=ANY ({{'{name, dept}'}});

If you want to filter data based on countries selected in a Multi-select widget, turn off prepared statements for this query and use the following format:

-- With prepared statements disabled
SELECT * FROM users WHERE country = ANY (ARRAY[{{MultiSelect2.selectedOptionValues.map(value => "'" + value + "'").join(', ')}}]);