Wiki source code of DB-Abfragen

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16.2	3	Database queries are similar to [[data sources>>doc:Sources]] (XML, CSV, JSON). The important difference is that they are not static, but read dynamically from a database. In principle, only queries or SELECT statements should be stored at this point. Other statements (INSERT, etc.) may work - but this varies from database type to database type and is not recommended. Instead, such statements should be made with the corresponding workflow action [[Database query>>doc:Formcycle.Designer.Workflow.Actions.SQLStatement]].
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	5	{{info}}
16.2	6	Before you can create a new database query, you must create a [[database connection >>doc:DBConnections]] if you have not done so already.
1.1	7	{{/info}}
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16.2	9	== Creating a database query ==
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	11	{{id name="data_db_query"/}}
16.2	12	{{figure image="data_db_query_de.png"}}Configuration screen for creating a database query in: (1) list of existing DB queries, (2) editor for defining the SQL query, (3) settings of the DB query, (4) console for testing the DB query.{{/figure}}
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16.2	15	* Open the module "Database queries" and click "New" {{ficon name="plus-circle-outline"/}} in the header of the list (see [[figure>>\|\|anchor="fig_data_db_query"]]).
	16	* The following data is needed for a Database query:
	17	Name**: A unique name for the database query
	18	Description**: An optional description for the database query
	19	Connection**: The [[Database connection>>doc:DBConnections]] that should be used
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16.2	21	* Enter the SQL statement to be executed for the query in the editor (see [[figure>>\|\|anchor="data_db_query"]]).
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16.2	23	The entered SQL statement is executed as a prepared statement, which prevents SQL injection attacks. You should not and need not use inverted commas (` or '). Also, you can use question marks ( ? ) as placeholders to build queries dynamically.
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16.2	25	[[Variables>>doc:Formcycle.UserInterface.Variables.WebHome]] can be used in the SQL statements.
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16.2	27	== Using the database query ==
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16.2	29	You can access the database query by making a HTTP request to the corresponding database servlet and providing the required parameters as GET parameters. The URL to the database query servlet is as follows.
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	31	{{code language="none"}}
	32	http://<server>/formcycle/datenabfragedb
	33	{{/code}}
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16.2	35	The servlet URL is displayed beneath the settings (see [[figure>>\|\|anchor="data_db_query"]]).
	36	The following URL parameters are supported:
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	38	{{table dataTypeAlpha="0" preSort="0-asc"}}
16.2	39	\|=Name of the paramter\|=Description\|=Required
	40	\|name\|Must match the name of the database query.\|Yes
	41	\|clientName\|Must match the name of the client used for creating this data source.\|Yes, if //projektId// is not given
	42	\|projektId\|Must match the ID of the form. This information can be seen by accessing the {{code language="javascript"}}XFC_METADATA.currentProject.id{{/code}} object from JavaScript.\|Yes, if //mandantName// is not given
	43	\|--sqlParameter--\|Alias for //queryParameter//. Should no longer be used in {{formcycle/}} version 6 and will most likely be removed in the next major release of {{formcycle/}}.\|No
	44	\|queryParameter\|When the query contains placeholders (question marks, {{code language="none"}}?{{/code}}), a list of parameters must be supplied for each placeholder. The number of items must match the number of parameters used in the SQL query. The items are separated with the delimiter as defined by the URL parameter //delimiter//.
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16.2	46	If possible the parameter //queryParameterValues// should be used for new projects instead of //queryParameter// because //queryParameter// will not be supported in a future version of {{formcycle/}}.\|No
	47	\|queryParameterValues\|Starting with {{formcycle/}} Version 6.6.3 this parameter can be used as an alternative to the parameters //queryParameter// and //delimiter//. Like these parameters, //queryParameterValues// is only required if placeholders in the form of a question mark {{code language="none"}}?{{/code}} are used within the SQL query. If this is the case, the individual query parameters are passed one after the other as a separate parameter //queryParameterValues//, which also eliminates the use of the parameter //delimiter//.\|No
	48	\|varName\|Allows you to change name of the JSON response object. If not given, a plain JSON object with the result data is returned.\|No
	49	\|delimiter\|The delimiter for the placeholder values, see //queryParameter//. Defaults to a comma {{code language="none"}},{{/code}}
	50	\|jsonPath {{version major="7" minor="3"/}}\|This parameter allows specifying a JSON path expression which will be applied to the returned result of the query on the server side. The example //$.returnValue[0]// returns the values of the first result of the query.\|No
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16.2	52	If possible the parameter //queryParameterValues// should be used for new projects instead of //delimiter// and //queryParameter// because //delimiter// will not be supported in a future version of {{formcycle/}}.\|No
1.1	53	{{/table}}
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16.2	55	When accessing a database servlet from a form, always use the database URL contained in the global object //XFC_METADATA//, see also the [[metadata>>doc:Formcycle.Designer.Form.CodingPanel.ScriptTab.FormMetadata]]. For example: {{code language="javascript"}}XFC_METADATA.urls.datasource_db{{/code}}.
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16.2	57	Further we recommend you use the script function {{jsdoc page="xutil" name="getdataquery"/}}, so you do not have to setup the servlet request manually. The result of the database query is returned as //JSON//.
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16.2	59	== Testing the query ==
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	61	{{info}}
16.2	62	For quick testing of the query the shortcut {{code language="none"}}Ctrl + Enter{{/code}} is provided.
1.1	63	{{/info}}
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16.2	65	Database queries can be tested directly from the configuration UI. For this purpose a test console is provided below the SQL editor (see [[figure>>\|\|anchor="fig_data_db_query"]]).
	66	In the header of the console there is a row of buttons for controling the query:
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16.2	68	* {{ficon name="database-search"/}}Perform query
	69	Runs the database query. If //query parameters// ({{code language="none"}}?{{/code}}) are provided the user will be prompted to input values vor those parameters. Otherwise the result of the query will be displayed directly in the //table view//.{{lightbox image="data_db_query_test_en.png" title="Run the given query"/}}
	70	* {{icon name="question"/}}Query parameters
	71	Mask for inputting values for query parameters. This option is only available if query parameters ({{code language="none"}}?{{/code}}) are used in the SQL query. The individual parameters will be enumerated in the SQL query. Clicking "User parameters for query" {{ficon name="arrow-right-bold-circle-outline2"/}} executes the query with the given parameters. The result will be displayed in the //table view//.
	72	{{lightbox image="data_db_query_test_param_en.png" title="Query parameters are enumerated"/}}
	73	Actual Query in the SQL editor:{{lightbox image="data_db_query_example_de.png" title="Example query"/}}
	74	* {{ficon name="table-large"/}}Table view
	75	Query result in table view{{lightbox image="data_db_query_test_table_en.png" title="Query result in table view"/}}
	76	* {{icon name="code"/}}Source code view
	77	Query result in JSON format{{lightbox image="data_db_query_test_code_en.png" title="Query result in JSON format"/}}
	78	* {{icon name="Terminal"/}}Generated SQL
	79	Displays the generated SQL statement with input parameter values{{lightbox image="data_db_query_test_sql_en.png" title="Displays the generated SQL statement with input parameter values"/}}
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16.2	81	== Selection form elements ==
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16.2	83	If you want to display the returned data as options of a [[selection element>>doc:Formcycle.Designer.Form.FormElements.Selection]], you can do so easily by opening the {{designer/}} and selecting the database query as the data source of the selection element.
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	85	{{info}}
16.2	86	Queries that are used in selection elements must not have a question mark "?". Queries with a "?" are not offered as a data source for selection elements.
1.1	87	{{/info}}
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16.2	89	{{figure image="data_db_query_designer_en.png"}}
	90	Using the result of a database query as the data source a select element in the {{designer case="dat"/}}.
1.1	91	{{/figure}}
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16.2	93	The result of the database query is used to create the options of the [[selection element>>doc:Formcycle.Designer.Form.FormElements.Selection]] in the following order:
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	95	{{box}}
16.2	96	Displayed value, submitted value, optional value 1, optional value 2, ...
1.1	97	{{/box}}
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16.2	99	All returned columns are added as the value of the HTML attribute //col0// (displayed value), //col1// (submitted value), //col2// (optional value 1), //col3// (optional value 2) etc. to the corresponding //option// element.
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16.2	101	The displayed value is visible to the user directly when selecting an option. The submitted value is the value of the HTML attribute //value// and it is sent when the form is submitted.
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16.2	103	Optional values returned by the database query may be access as follows with //JavaScript//.
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	105	{{code language="javascript"}}
16.2	106	$('[name=sel2]').find('option:selected').attr('col2') // Selects the active option of the selection element named 'sel2' and returns the first optional value.
1.1	107	{{/code}}
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16.2	109	== Examples ==
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	111	{{code language="sql"}}
16.2	112	select name, first_name from table where first_name like (?)
1.1	113	{{/code}}
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16.2	115	This SQL statement returns the names of all persons with a certain first name. The first name to search for is specified via an URL parameter.
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16.2	117	URL for running the query:
	118	{{code language="none"}}http://myserver/formcycle/datenquelledb?mandantName=myself&name=demo&queryParameterValues=Robinson{{/code}}
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	121	{{code language="sql"}}
16.2	122	select name, first_name from table where id = ?
1.1	123	{{/code}}
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16.2	125	Retrieves the name of a person with a certain ID. The ID is given as an URL parameter.
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16.2	127	URL for running the query:
	128	{{code language="none"}}http://myserver/formcycle/datenquelledb?mandantName=myself&name=demo&queryParameterValues=100{{/code}}
1.1	129	\\
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	131	{{code language="sql"}}
16.2	132	select name, first_name from table where city like(?) AND zip = ?
1.1	133	{{/code}}
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16.2	135	Retrieves the names of all persons that live in certain city. The city and the ZIP code are given as URL parameters.
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16.2	137	URL for running the query:
	138	{{code language="none"}}http://myserver/formcycle/datenquelledb?mandantName=myself&name=demo&queryParameterValues=Paris&queryParameterValues=75001{{/code}}
1.1	139	\\
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	141	{{code language="sql"}}
	142	select name, vorname from tabelle where ort like concat(?, '%')
	143	{{/code}}
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16.2	145	This SQL statement returns the names of all persons who live in a place that starts with the given characters. The '%' character serves as a wildcard for any number of characters. Depending on the DBMS used, the syntax may differ slightly (here: MySQL). The requested value is passed via URL parameters.
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16.2	147	URL for running the query:
	148	{{code language="none"}}http://myserver/formcycle/datenquelledb?mandantName=myself&name=demo&queryParameterValues=Par{{/code}}
	149	\\
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	151	{{code language="sql"}}
	152	select name, vorname from tabelle where lower(ort) like concat('%', lower(?), '%')
	153	{{/code}}
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16.2	155	This SQL statement returns the names of all persons who live in a place that contains the given characters. Upper/lower case spelling is irrelevant becauce the statement converts both, the value column and the actual filter value to lower case (lower(...)). The requested value is passed via URL parameters.
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16.2	157	URL for running the query:
	158	{{code language="none"}}http://myserver/formcycle/datenquelledb?mandantName=myself&name=demo&queryParameterValues=aRi{{/code}}