![]() Remember to beforehand check that the value leaves no opening for SQL-injection!įor parameter values, a better approach is to use bind variables such as in the following code: declare Changing the SQL-statement’s text in this way is only recommended when making changes that lead to totally different SQL-statements, such as changing the source table’s name. For instance, through SQL injection stored procedures can be called or sensitive filters circumvented.Īlso, unnecessary use of dynamic SQL reduces re-use of previously created execution plans, significantly lowering throughput in high-volume environments. SQL injection is an attack vector that chooses the variable text in the SQL statement such that it is still a valid SQL-statement, but with a totally different meaning. However, such an approach introduces security risks for SQL-injection that need to balanced. 'select count(*), count(distinct code) from where code = ''' The brute force approach is to change the SQL-statement’s text according to your needs, such as: declare Often, you will want to provide parameter values to a dynamic SQL-statement. ![]() Showing that there are 44 journals across all selected Exact Online companies.Īlternatively, you can also execute PSQL-statements dynamically which store outcome in a table to be queried later or use a stored procedure such as dbms_output.put_line. There are 44 journals with 17 distinct codes. The output tab of the Query Tool will include output such as: 'select count(*), count(distinct code) from l_cnt1, l_cnt2Īfter the into you can list output parameters to contain the output of the SQL-statement as a select-statement. In case you want to retrieve the outcome of the dynamic SQL-statement, the output can be stored into PSQL-variables as in: declare Using dynamic SQL without exchanging data is typically only useful to run DML-statements such as an delete or a stored procedure that performs and stores calculations. It will return a value like 56 (journals). 'select count(*) from executed, the Invantive parser will check the validity of the text as a SQL-statement and execute it. The dynamic SQL variant has a text constant containing the statement and then executes it: begin The first example of dynamic SQL is to count the number of journals in the Exact Online company using a dynamic SQL statement. Or for instance using PSQL-binding: declare The constant 10 can be replaced by a parameter for use with for instance the Invantive Query Tool as in: select count(*) No need for dynamic SQL when different valuesĭynamic SQL is not needed when solely parameters for a query or update statement need to be different that functionality is automatically provided through parameter-binding such as: select count(*) ![]() Typical Use Cases of Dynamic SQLĭynamic SQL- and PSQL-statements are typically used when the logic must vary depending on parameters provided and requires a different SQL-statement that must be parsed and executed. When executing DDL-statements caution has to be applied to avoid locking issues or even deadlocks being generated.ĭynamic execution of SQL and PSQL-statements requires more time and attention regarding the correctness of the statements being executed, since trivial parts of the correctness check such as syntax are delayed from design-time to runtime.įor this topic, we will use an Exact Online database, but the samples can easily be mapped onto any supported cloud- or database-platform. The SQL-grammar describes the syntax of the execute immediate statement.Īn execute immediate statement can execute queries, stored procedures, DML-statements and DDL-statements such as create procedure or create table. Dynamic SQL statements execute within the security context of the calling PSQL block.ĭynamic SQL and PSQL statements on Invantive using the execute immediate statement. instead of Invantive’s SQL/PSQL engine please refer to Evaluate Native SQL Statements from Invantive PSQL for practical guidance.ĭynamic SQL statements can use all Invantive SQL and PSQL features. This topic provides some samples on use of dynamic SQL.įor execution of native SQL, T-SQL, PL/SQL, PL/pgSQL statements on SQL Server, PostgreSQL, Oracle, etc. The industry-term for such statements is “Dynamic SQL”. Invantive SQL/PSQL provides means to execute SQL and PSQL-statements that are dynamically generated.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |