Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Image | Name | Birth date | Death date | Brief biography |
| --- | --- | --- | --- | --- |
|  | Harriet Churchill | October 1679 | October 1679 | Died an infant |
|  | Henrietta Churchill (later Godolphin), 2nd Duchess of Marlborough in her own right | 19 July 1681 | 24 October 1733 | Married The Hon. Francis Godolphin (later Viscount Rialton by courtesy and 2nd Earl of Godolphin respectively) on 23 April 1698. Their son, William, Marquess of Blandford died in 1731; their daughter Henrietta married Thomas Pelham-Holles, 1st Duke of Newcastle-upon-Tyne; their daughter Mary married Thomas Osborne, 4th Duke of Leeds. |
|  | Anne Churchill (later Spencer) | 27 February 1683 | 15 April 1716 | Anne married the Whig politician Charles Spencer, 3rd Earl of Sunderland on 14 September 1699. After her sister Henrietta's death in 1733, their son, Charles became 3rd Duke of Marlborough. Their son John is the ancestor of the Earls Spencer and thus of Diana, Princess of Wales. Their daughter Diana nearly married Frederick, Prince of Wales, but when the plan failed, married Lord John Russell, later 4th Duke of Bedford. |
|  | John Churchill, Marquess of Blandford | 13 February 1686 | 20 February 1703 | John, Marquess of Blandford was the heir to the Dukedom of Marlborough. He died unmarried and without children in 1703, so the dukedom passed to Marlborough's eldest daughter, Henrietta, after his death in 1703. |
|  | Elizabeth Churchill (later Egerton) | 15 March 1687 | 22 March 1738 | Married Scroop Egerton, 4th Earl of Bridgewater (from 1720, 1st Duke of Bridgewater) on 9 February 1703, leaving issue |
|  | Mary Churchill (later Montagu) | 15 July 1689 | 14 May 1729 | Married John Montagu, 2nd Duke of Montagu on 17 March 1705, leaving issue |
| — | Charles Churchill | 19 August 1690 | 22 May 1692 | Died an infant |
Question:
what is the number of children sarah churchill had?
Answer:
7