Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE Accounts ( Account_ID INTEGER, Statement_ID INTEGER, Account_Details VARCHAR(255) )
TABLE: CREATE TABLE Ref_Budget_Codes ( Budget_Type_Code CHAR(15), Budget_Type_Description VARCHAR(255) )
TABLE: CREATE TABLE Documents_with_Expenses ( Document_ID INTEGER, Budget_Type_Code CHAR(15), Document_Details VARCHAR(255) )
TABLE: CREATE TABLE Ref_Document_Types ( Document_Type_Code CHAR(15), Document_Type_Name VARCHAR(255), Document_Type_Description VARCHAR(255) )
TABLE: CREATE TABLE Statements ( Statement_ID INTEGER, Statement_Details VARCHAR(255) )
TABLE: CREATE TABLE Documents ( Document_ID INTEGER, Document_Type_Code CHAR(15), Project_ID INTEGER, Document_Date DATETIME, Document_Name VARCHAR(255), Document_Description VARCHAR(255), Other_Details VARCHAR(255) )
TABLE: CREATE TABLE Projects ( Project_ID INTEGER, Project_Details VARCHAR(255) )

### Question ###
Show the number of documents for different budget type code in a pie chart.

### Accurate SQL ###

SELECT T1.Budget_Type_Code, COUNT(T1.Budget_Type_Code) FROM Documents_with_Expenses AS T1 JOIN Ref_Budget_Codes AS T2 ON T1.Budget_Type_Code = T2.Budget_Type_Code GROUP BY T1.Budget_Type_Code