SQL is the industry standard language for accessing and updating database data and ESQL is a language derived from SQL Version 3, particularly suited to. Use ESQL statements and functions to read from, write to, and modify databases from your message flows. Customize processing implemented by the Compute, Database, DatabaseInput, and Filter nodes in your message flows by coding ESQL.
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This message is provided in XML source format with tags and attributessee Example message. Declare a reference pointer as shown in the following example: The following example shows repeating fields being accessed in an input message tree: While is certainly not the norm, it can happen, for example in case of version differences between the tooling and the runtime.
Takes a character value, interprets it as an SQL statement, and executes it. For further information, see Creating dynamic field references.
Interaction with databases using ESQL
You can improve message flow performance with ESQL by using some optimization techniques. Unless otherwise stated, these guidelines apply to messages in all message domains except the BLOB domain, for which you can implement a limited iibm of actions. Skip to content United States. The topics specific to the MRM domain use the message that is created in the following sample: Some of the built-in nodes enable you to customize the processing that they provide.
You can use reference variables instead, which maintain a pointer into the array and which can edql be reused; for example:.
IBMintegrationMedia channel For community support, visit: These functions are expensive in performance terms, so minimizing their use can help to improve performance.
You can use Esq, statements to manipulate message trees, update databases, or interact with nodes. If you are accessing or creating consecutive fields or records, you can solve this problem by using reference variables. Evaluates a condition expression, and if it is TRUE executes a sequence of statements. However, it is expensive in terms of CPU use, because it involves the statement being run twice.
When you create a message flow, you include input nodes that receive the messages and, optionally, output nodes that send out new or updated messages. Performance is affected by the SET statement being used to create many more fields, as shown in the following example:. DBData[A] increases ib processing time significantly:.
Join The Discussion Cancel reply Your email address will not be published. Where possible, also avoid executing the same concatenations repeatedly, by storing intermediate results in variables.
Top 3 hidden treasures (in ESQL)
Defining message flow content. Evaluates a source expression, and assigns the result to the target entity. Detaches and destroys a portion of a message tree, allowing its memory to be reused. Deletes rows from a table in an external database based on a search condition. Takes a character value and passes it as an SQL statement to an external database. Message tree manipulation statements: The following example shows the ESQL that can be used to reduce the number of navigations when creating new output message tree fields:.
By avoiding the use of array subscripts wherever possible, you can improve the performance of your ESQL code. If examples include a reference to MRM, they assume that you have modeled the message in the MRM and that you have set the names of the MRM objects to be identical to the names of the corresponding tags or attributes in the XML source message. For domain-specific information, use the appropriate link in the previous list.
Unless stated otherwise, the principals illustrated are the same for all message domains.
Everything described below has been part of IIB for some time. If ib expression evaluates to TRUE, executes the statements again. This technique also helps to reduce memory usage.
Processes a set of statements based on the result of evaluating condition expressions. The ComputeDatabaseDatabaseInputand Filter nodes require you to provide a minimum level of ESQL, and you can provide much more than the minimum to control precisely the behavior of each node.