Deleting data. The Delete class

Glossary Item Box

Introduction

The Terrasoft.Core.DB.Delete class is used to build queries for deleting records in bpm’online database tables. As a result of creating and configuring the instance of this class, the DELETE SQL-expression query to the application database will be built.

The Terrasoft.Core.DB.Delete class

NOTE

Use the “.NET class libraries of platform core” documentation to access the full list of the Delete class methods and properties, its parent classes and the implemented interfaces.

Constructors

public Delete(UserConnection userConnection) – creates a class instance using UserConnection
public Delete(Delete source) – creates a class instance that is a clone of the instance passed as an argument

Properties

Table 1. Primary properties of the class

Property	Type	Description
UserConnection	Terrasoft.Core.UserConnection	The current user connection at the moment of executing the query.
Condition	Terrasoft.Core.DB.QueryCondition	Condition of Where expression in the query.
HasCondition	bool	Determines whether Where expression is available in the query.
Source.	Terrasoft.Core.DB.ModifyQuerySource	The query data source.

Methods

Table 2. Primary methods of the class

Methods		Description
string GetSqlText()		Returns the SQL text of the current query.
void BuildSqlText(StringBuilder sb)		Generates the query text via the StringBuilder instance.
void ResetCachedSqlText()		Clears the cached text of the query.
QueryParameterCollection GetUsingParameters()		Returns the collection of parameters used by the query.
int Execute()		Executes the query. Returns the number of records involved by the query.
int Execute(DBExecutor dbExecutor)		Executes the query using the DBExecutor instance. Returns the number of records involved by the query.
QueryCondition Where() QueryCondition Where(string sourceColumnAlias) QueryCondition Where(string sourceAlias, string sourceColumnAlias) QueryCondition Where(Select subSelect) QueryCondition Where(Query subSelectQuery) QueryCondition Where(QueryColumnExpression columnExpression) Query Where(QueryCondition condition)		Adds the initial condition to the current query. Parameters: sourceColumnAlias – an alias of the column for which the condition is added sourceAlias – the alias of the source subSelect – a subquery of the data selection, for whose results the condition is added subSelectQuery – the subquery, for whose results the condition is added columnExpression – the expression, for whose results the condition is added condition – the query condition
QueryCondition And() QueryCondition And(string sourceColumnAlias) QueryCondition And(string sourceAlias, string sourceColumnAlias) QueryCondition And(Select subSelect) QueryCondition And(Query subSelectQuery) QueryCondition And(QueryParameter parameter) QueryCondition And(QueryColumnExpression columnExpression) Query And(QueryCondition condition)		Adds the condition (predicate) to the current query condition using the AND logical operation. Parameters: sourceColumnAlias – an alias of the column, for which the predicate is added sourceAlias – the alias of the source subSelect – the data selection subquery used as a predicate subSelectQuery – the subquery used as a predicate parameter – parameter that the predicate is added to columnExpression – the expression used as a predicate condition – the query condition
QueryCondition Or() QueryCondition Or(string sourceColumnAlias) QueryCondition Or(string sourceAlias, string sourceColumnAlias) QueryCondition Or(Select subSelect) QueryCondition Or(Query subSelectQuery) QueryCondition Or(QueryParameter parameter) QueryCondition Or(QueryColumnExpression columnExpression) Query Or(QueryCondition condition)		Adds the condition (predicate) to the current query condition using the OR logical operation. Parameters: sourceColumnAlias – an alias of the column, for which the predicate is added sourceAlias – the alias of the source subSelect – the data selection subquery used as a predicate subSelectQuery – the subquery used as a predicate parameter – parameter that the predicate is added to columnExpression – the expression used as a predicate condition – the query condition
Delete From(string schemaName) Delete From(ModifyQuerySource source)		Adds the data source to the current query. Returns the current Delete instance. Parameters: schemaName— schema name (tables, views) source – the data source

Use cases

You can download the package with the configuration web serice implementing the below described cases using the following link.

ATTENTION

In most cases, the request for deletion should contain the Where condition, which specifies which records exactly should be deleted. Otherwise, all records will be deleted.

Example 1

Receive the SQL-query text.

public string GetSqlTextExample(string name)
{
    var result = "";
    var delete = new Delete(UserConnection)
        .From("Contact")
        .Where("Name").IsEqual(Column.Const(name));
    result = delete.GetSqlText();
    return result;
}

Example 2

Change the contact name for a new one.

public string DeleteContacts(string name)
{
    var delete = new Delete(UserConnection)
        .From("Contact")
        .Where("Name").IsEqual(Column.Const(name));
    var cnt = delete.Execute();
    return $"Contacts with name {name} were deleted. {cnt} rows affected";
}

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Documentation

Deleting data. The Delete class

Introduction

The Terrasoft.Core.DB.Delete class

Constructors

Properties

Methods

Use cases

Example 1

Example 2

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